Pool Frog Reintroduction Plan for Thompson Common, Norfolk

Version: 20 March 2015

Pool Frog Reintroduction Plan for Thompson Common, Norfolk

Version: 20 March 2015

J.M.R. Baker & J. Foster

Suggested citation: Baker, J.M.R. & Foster, J. (2015). Pool Frog Reintroduction Plan for Thompson Common, Norfolk. Version: 20 March 2015. Unpublished report. Amphibian and Reptile Conservation, Bournemouth.

Contents

1. SUMMARY ...... 1 2. INTRODUCTION AND BACKGROUND ...... 3 2.1. Project origin and governance ...... 3 2.2. Pool frog Reintroduction Strategy and international context ...... 3 2.3. Reintroduction guidelines ...... 4 3. RATIONALE FOR A SECOND REINTRODUCTION ...... 5 3.1. Summary of rationale ...... 5 3.2. Progress under the national biodiversity strategy...... 5 3.3. Progress towards favourable conservation status ...... 5 4. SITE SELECTION FOR THE SECOND REINTRODUCTION...... 7 4.1. Rationale for the selection of Thompson Common ...... 7 4.2. Release location ...... 7 4.3. Addressing extinction factors at Thompson Common ...... 8 5. REINTRODUCTION METHODS...... 10 5.1. Overview ...... 10 5.2. Overview – habitat management ...... 10 5.3. Overview – translocation ...... 10 5.4. Overview – monitoring ...... 10 6. HABITAT MANAGEMENT ...... 11 6.1. Pre-release habitat management measures ...... 11 6.2. Proposed short-term habitat management measures ...... 11 6.3. Proposed long-term habitat management measures ...... 13 7. TRANSLOCATION AND HEAD-STARTING ...... 14 7.1. Overview of head-starting ...... 14 7.2. Collection of eggs ...... 14 7.3. Hatching and initial growth (indoors) ...... 14 7.4. Growth in artificial ponds (outdoors) ...... 14 7.5. Release of metamorphs ...... 14 7.6. Locations of artificial ponds ...... 15 7.7. Managing disease and health risks ...... 15 8. MONITORING ...... 16 8.1. Post-release monitoring of pool frogs ...... 16 8.2. Monitoring other amphibian species ...... 16 8.3. Monitoring habitat ...... 17 8.4. Monitoring impacts on other SSSI features ...... 17 8.5. Indicators of success ...... 17 9. REGULATORY COMPLIANCE ...... 19 9.1. Species and site legal protection ...... 19 9.2. Head-starting and translocation of a European Protected Species ...... 19 9.3. Implications of impacts and potential impacts on a protected site ...... 19 10. IMPACT OF REINTRODUCTION ON SSSI/SAC FEATURES ...... 20 10.1. Consistency with Views About Management ...... 20 10.2. Operations requiring consent ...... 20 10.3. Avoidance of designated features ...... 21 10.4. Risk of harm to designated features ...... 22 10.5. Reintroduction site benefits ...... 23 10.6. Habitats Regulations Assessment ...... 30 11. COMMUNICATIONS ...... 31 11.1. Communications strategy under the first reintroduction ...... 31 11.2. Planned communications for the second reintroduction ...... 31 12. ENGAGEMENT WITH ZOOLOGICAL COLLECTIONS ...... 33

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12.1. ‘Hybrid’ pool frogs in zoological collections ...... 33 12.2. Supply of northern pool frogs to zoological collections ...... 33 12.3. Legal and contractual regulation of captive stock ...... 33 13. ACKNOWLEDGEMENTS ...... 34 14. LITERATURE ...... 34 APPENDIX 1. STEPS REQUIRED FOR SUCCESSFUL IMPLEMENTATION ...... 36 APPENDIX 2. EVALUATION AGAINST IUCN REINTRODUCTION GUIDELINES ...... 37 Annex 3. Deciding when translocation is an acceptable option ...... 37 Annex 3.1 Introduction ...... 37 Annex 3.2 Assessing extinction causes ...... 38 Annex 3.3 Considering alternatives ...... 40 Annex 4 Planning a translocation ...... 41 Annex 5 Feasibility and design ...... 42 Annex 5.1 Background biological and ecological knowledge...... 42 5.2 Models, precedents for same/similar species ...... 42 5.3 Habitat ...... 43 5.4 Climate requirements ...... 45 5.5 Founders ...... 46 5.6 Disease and parasite considerations ...... 47 Annex 6 Risk assessment...... 49 6.1 Assessing the risk landscape ...... 49 6.2 Risks to the source population ...... 49 6.3 The ecological consequences of translocation ...... 49 6.4 Disease risk ...... 50 6.5 Association invasion risk ...... 50 6.6 Gene escape ...... 51 6.7 Socio-economic risks ...... 51 6.8 Financial risks ...... 51 Annex 7 Release and implementation ...... 51 Annex 8 Outcome assessment and continuing management ...... 54 8.1 Survey / monitoring before release ...... 54 8.2 Monitoring after release ...... 55 8.3 Continuing management ...... 57 Annex 9 Dissemination of information ...... 58 APPENDIX 3: CAPTIVE LOAN AGREEMENT ...... 60

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1. Summary

This reintroduction plan sets out the rationale and procedures required for a second reintroduction of the northern pool frog Pelophylax lessonae in England.

The northern pool frog has been reintroduced to England as part of a programme guided by a published strategy (Reintroduction strategy for the pool frog Rana lessonae in England, Buckley & Foster, 2005; termed the Reintroduction Strategy here). The species currently persists at one site in Norfolk, established via releases of frogs obtained from Sweden during the years 2005 to 2008. The proposed second reintroduction, the subject of the current plan, constitutes progress towards the recovery of a European protected species prioritised by England’s national biodiversity strategy (Biodiversity 2020). This second reintroduction would increase the resilience of the English population of pool frogs by providing an additional site, thereby increasing range and population size and reducing extinction risk.

The proposed second reintroduction closely follows the principles and methods detailed in the Reintroduction Strategy. The plans have been updated according to recent evidence and reintroduction practice. The plans have also been thoroughly evaluated to ensure compliance with the latest national and international standards, with particular reference to the Guidelines for Reintroductions and Other Conservation Translocations (IUCN/SSC, 2013). As a result, the project managers believe the pool frog reintroduction can be regarded as a model programme for species recovery. The likely benefits and potential risks of the proposed reintroduction have been assessed, and clearly indicate significant gains for amphibian conservation with minimal risks.

The area selected for the reintroduction is part of Thompson Common, in Breckland District, Norfolk. This site is a Norfolk Wildlife Trust (NWT) nature reserve, within Thompson Water, Carr and Common Site of Special Scientific Interest (SSSI) and part of the Norfolk Valley Fens Special Area of Conservation (SAC). Thompson Common was the last site where the native pool frog was known to survive in the wild in England, before going extinct in the mid-1990s. The probable extinction factors have been addressed, principally by habitat management carried out by NWT.

Only a small part of Thompson Common has been selected as the release area largely on the basis of habitat suitability, and this area is not open to the public. However, the intention is that the pool frogs will eventually disperse to and establish in open access parts of the reserve (indeed, where they occurred in the recent past), where they can be appreciated by the public.

To establish a second population, pool frogs will be taken from the population already established in Norfolk under the first reintroduction. This second reintroduction proposes to ‘head-start’ tadpoles to capitalise on the high reproductive potential of amphibians while minimising the impact of stock removal from the source population. Given the recent increase in concern over amphibian diseases globally, the project has been carefully designed to minimise risks associated with pathogen transfer. On the basis of current information, the reintroduction poses negligible disease risks to the pool frogs subject to release and wildlife at the release site. Further detailed assessment of disease risks, based on ongoing work by the Institute of Zoology, London, will follow shortly.

The second reintroduction includes habitat management measures for the short- and long- term, although the extent of these is conditional upon how vegetation develops. Short-term management will entail mechanical intervention to create open pond habitat. In the long- term further mechanical intervention is also likely to be needed. This will involve removal of vegetation and superficial debris to maintain ponds in an early successional stage. Grazing will be required to manage both aquatic and terrestrial vegetation. Although the nature reserve’s Management Plan includes this, the pool frog reintroduction managers will need scope to increase grazing pressure over the reintroduction area if necessary, after

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consultation with the reserve manager to ensure it is done in a manner consistent with broader management aims.

Given that the pool frog is a European Protected Species and the reintroduction area lies within a protected wildlife site, the proposed reintroduction and associated habitat management proposals are subject to various procedures and regulatory steps. Translocating the pool frog itself will require a ‘conservation licence’ (issued under the Conservation of Habitats and Species Regulations 2010 [as amended]) to permit the taking, possession and release of head-started tadpoles at a site other than site of capture. Regarding site protection, the reintroduction must be approved by an Appropriate Assessment to permit the reintroduction on a Special Area of Conservation. Elements of the reintroduction (annual releases of metamorphs, short- and long-term habitat management measures) will require specific consents to ensure that they do not harm the interest features of the SSSI. Information required for an Appropriate Assessment and for future consents for specific management intervention is given in the current report.

The reintroduction of the northern pool frog to Thompson Common and the associated habitat management measures will have wider and noteworthy benefits. The pool frog’s presence at Thompson Common was dependent on the habitat conditions that also make it such a significant pond site. Hence, management measures proposed here will benefit many other species dependent on the same habitat.

The reintroduction will be monitored to assess its progress and to permit adaptive habitat and species management as required. This will involve monitoring of the population status of released pool frogs and resident amphibian species, and an assessment of habitat condition. The health status of pool frogs will be monitored according to a risk-based approach. The methods for monitoring will closely follow those developed in the first reintroduction.

This reintroduction plan includes a communications strategy, to inform target audiences of key messages relating to the project. Given that the initial reintroduction area is not open access, we wish to allow interested people to easily see pool frogs elsewhere. Therefore, we will engage with publicly accessible zoological collections, which will be provided with a small number of animals from the head-started stock to provide educational exhibits. These animals will be loaned to zoological collections and their possession regulated by licence and loan agreements.

The project will continue to be governed by an expert group, and will continue to take advice from regulatory and scientific authorities. The current document constitutes a critical part of the licence application to Natural England. Finally, a detailed account of all project stages will be maintained. This will be done so that the reintroduction can be documented in the scientific and practitioner literature, noting methodological points of interest as well as the overall biological and conservation outcomes.

Development of this reintroduction plan has been managed by Amphibian and Reptile Conservation, with the generous support of the Heritage Lottery Fund through the Breaking New Ground project.

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2. Introduction and background

2.1. Project origin and governance The proposal for a second reintroduction of the northern pool frog arises from its status as a schedule IVa species on the EC Habitats Directive, and its listing in UK legislation as a species of principal importance for biodiversity (see further detail below). The northern pool frog is the UK’s rarest native amphibian and currently exists at only one site. There is therefore an imperative to enhance its status in the UK, and thereby improve its status in a European context. Biodiversity 2020, the government’s strategy for biodiversity in England, encourages projects to enhance the status of species at risk of extinction. The second reintroduction has been developed and is led by Amphibian and Reptile Conservation, assisted by the Pool Frog Expert Group, which represents a range of relevant authorities. Amphibian and Reptile Conservation have overall responsibility for the project. There has been and will continue to be a substantial input from the Norfolk Wildlife Trust, which manages the proposed reintroduction site. The Heritage Lottery Fund (via the Breaking New Ground Project), Norfolk Wildlife Trust and Amphibian and Reptile Conservation have funded the development of the current document and will fund its implementation. The project has been developed according to evidence and good practice in reintroductions, and the managers believe it represents a model project. All reintroduction activities will be documented so that project progress and outcomes can be communicated to specialist and public audiences. The current document constitutes a critical part of the licence application to Natural England to allow the reintroduction to proceed, effectively acting as a Method Statement.

2.2. Pool frog Reintroduction Strategy and international context The native status of the pool frog in England was recognised only relatively recently (Beebee et al., 2005). Several independent lines of research concluded that pool frogs from populations in East Anglia were part of a northern clade of the species, hereinafter referred to as the northern pool frog when it is necessary to distinguish it from populations that have been introduced to England from other parts of the species range. Shortly before this recognition, in the late 1990s, the species became extinct in England. Since then the northern pool frog has been subject to a reintroduction programme guided by a published strategy (Buckley & Foster, 2005). This Reintroduction Strategy includes:  A summary of the history and research into the status of the pool frog in England  Aims and objectives of the reintroduction programme  An assessment of the reintroduction against published guidelines  Selection of reintroduction sites  Considerations of source stock  Proposals for post-release monitoring.

Under the European “Habitats Directive” (Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Flora and Fauna) the pool frog classed as a species of Community interest, being listed on Annex IVa of the Directive. In the UK, such species are termed European Protected Species. Amongst other things, the Habitats Directive requires Member States to implement strict protection, to undertake to restore the species to a favourable conservation status, and to monitor the conservation status of pool frogs. Drawing on this, the Reintroduction Strategy expresses its overall aim in these terms: to restore the pool frog to a favourable conservation status in England. The Habitats Directive defines conservation status as “favourable” when certain conditions are met. Essentially these relate to population size, range, habitat extent and future prospects. These elements were detailed in the Reintroduction Strategy, are summarised in Table 1 below, and discussed further in section 3.3..

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Table 1. Aim, objective and targets of the Reintroduction Strategy (Buckley & Foster, 2005). Aim Restore the pool frog to a favourable conservation status in England. Objective Restore populations to three sites in the likely former range of the species. Targets  The northern clade pool frog needs to be present as viable populations on a series of representative sites to form a robust distribution that allows for climate change and reflects scope for natural changes in range.  The species needs to be common and have a wide distribution around key sites.  Appropriate habitat management should be in place to ensure the long-term survival of the populations as viable components of the habitat.

The Reintroduction Strategy opted to use stock from Sweden to translocate to England. From 2005 to2008 pool frogs were translocated into a carefully selected and specifically managed site at a confidential location in Norfolk (the initial reintroduction site). Post- release monitoring has shown that a population of pool frogs has become established (e.g. Baker, 2014a).

2.3. Reintroduction guidelines The Reintroduction Strategy was assessed and drafted against guidance produced by the Joint Nature Conservation Committee (McLean, 2003) which provides a process for carrying out conservation translocations. The JNCC guidance was based on the IUCN’s Guidelines for Re-introductions (IUCN, 1995) but since then the latter have been updated as Guidelines for Reintroductions and other Conservation Translocations (IUCN/SSC, 2013). The pool frog reintroduction programme continues to adhere to best practice guidance and so the plan for the proposed second reintroduction discussed here is documented against annexes 3-9 of the most recent guidelines in Appendix 2 of the current document. Annexes 1 and 2 of the IUCN/SSC (2013) guidelines deal with background information and definitions, and are not included here.

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3. Rationale for a second reintroduction

3.1. Summary of rationale Establishing a second population of pool frogs is desirable in order to:  Make progress under “Outcome 3” of the England’s national biodiversity strategy, Biodiversity 2020.  Make progress towards favourable conservation status for pool frogs, under the Habitats Directive.

3.2. Progress under the national biodiversity strategy National strategy for wildlife recovery in England is laid out in Biodiversity 2020: A strategy for England’s wildlife and ecosystem services (Defra, 2011). This includes a set of high- level outcomes. Outcome 3 states that: By 2020, we will see an overall improvement in the status of our wildlife and will have prevented further human-induced extinctions of known threatened species. The strategy acknowledges that specific tailored actions are required for the recovery of some priority species and makes these priority actions. The pool frog has been identified as a priority species by the Natural Environment and Rural Communities Act 2006, by listing under Section 41. Given extinction from its former natural range in England, its specific habitat requirements and limited dispersal abilities, pool frog restoration requires deliberate releases to new areas, as well as other measures, to establish new populations.

Biodiversity 2020 gives greatest priority to species at risk for which England has a particular international responsibility. Restoring pool frogs to Thompson Common will coincide with habitat restoration measures, helping to meet both habitat and species restoration outcomes identified under the Biodiversity 2020 strategy. The northern form of the pool frog has a very limited global range (Buckley & Foster, 2005), making its status in England of international significance. The proposal to reintroduce pool frogs to a second site has been recommended by the England Herpetofauna Taxon Group, which provides advice to the Species Technical Advisory Group, which in turn advises the Terrestrial Biodiversity Group. The latter is one of the key governance points in the implementation of Biodiversity 2020. Currently, pool frogs are deemed to be around Step 5-6 on the “Recovery Curve,” a method used in Biodiversity 2020 implementation to assess species recovery progress on a scale of 0 to 9.

Biodiversity 2020 prioritises species at most risk of extinction. Currently the northern pool frog in England is confined to a single site. Population fluctuations driven by stochastic events could result in the loss of this population and, hence, national extinction. To secure the future of the pool frog in England it is essential to establish additional populations. Translocation is the most appropriate way to achieve this.

3.3. Progress towards favourable conservation status Article 2 of the Habitats Directive states that conservation status is regarded as favourable when:  population dynamics data on the species concerned indicate that it is maintaining itself on a long-term basis as a viable component of its natural habitats, and  the natural range of the species is neither being reduced nor is likely to be reduced for the foreseeable future, and  there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis.

The most recent round of reporting under the Habitats Directive (Third Report by the United Kingdom under Article 17 on the implementation of the Directive from January 2007 to December 2012; JNCC website: www.jncc.defra.gov.uk, accessed March 2015) the conservation status of the pool frog in the UK was assessed as ‘bad’, because range and population parameters were judged as ‘bad’. The proposed second reintroduction will

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achieve an expansion in range and an increase in population size, thus improving conservation status, as discussed below:

Increase in range: Post-release monitoring indicates that the introduced pool frogs are relatively sedentary, probably in part due to the specificity of their habitat requirements. The first reintroduction site contains many high quality ponds within a discrete core area that is specifically managed to maintain a relatively open, semi-natural habitat. Even within this site, the frogs have tended to aggregate on a small proportion of ponds rather than spread through the whole of the core area. Young pool frogs have been found, on occasions, in ponds immediately beyond the core area (25-100 m from the core site boundary) but occupation of these has been temporary. Two adult frogs were found in a pond 300 m beyond the core site boundary, a distance of 500-640 m from the location of the original releases but they subsequently returned to the core site. Overall, there is no indication that the reintroduced population is likely to become established beyond the core site or to migrate through surrounding habitat to other suitable sites. The habitat required by pool frogs is unlikely to occur in present day landscapes beyond specifically managed nature reserves or dedicated sites, hence significant range increase is unlikely to occur without deliberate releases.

Increase in population size: The favourable reference value for the population parameter is 10,000. The first reintroduction site is not large enough to support this number of pool frogs. Although negotiations are in progress to increase the extent of suitable habitat at the first site this, alone, will still be insufficient to meet the favourable reference value. Progress towards this can be met only by translocating frogs to additional sites in the likely former range. Having these numbers distributed over two (or more) sites would also decrease extinction risk so long as each site supports a robust population.

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4. Site selection for the second reintroduction

4.1. Rationale for the selection of Thompson Common Thompson Common has been selected as the location for the second reintroduction for two main reasons:  It was the location of the last known native pool frog population, and therefore inherently should be subject to a range restoration attempt; and  It has been identified as the most suitable site in a review process.

Thompson Common comprises a peri-glacial geomorphology creating a unique wildlife site that supports outstanding assemblages of invertebrates and uncommon aquatic plants and plant communities (Gibbons, 2004; Yaxley, 2013). The site’s history, ecology, flora and fauna are summarised in the site Management Plan (Norfolk Wildlife Trust, in prep.). Until recently, the pool frog was the most significant vertebrate present in conservation terms. Its reintroduction is included in the Management Plan, and therefore the current plan is an important element of fulfilling the site’s objectives. The probable reasons for the pool frog’s extinction have been addressed (see below), and so there is a clear case for reintroduction.

Prior to the initial translocation from Sweden, six potential reintroduction sites were reviewed for their potential to support pool frogs (see Buckley & Foster, 2005) and the first reintroduction site was thus selected. A more recent review undertaken to support the current reintroduction (Baker, 2012) assessed in detail five sites originally considered for the first reintroduction, along with five additional potentially suitable sites. Review criteria included current habitat quality and extent, water quality, management, land manager views, and any other points likely to influence suitability for reintroduction. This review concluded that Thompson Common currently offers the greatest and most immediate potential in terms of habitat suitability, management and consistency with site conservation objectives. Given the results of this assessment and the fact that pool frogs used to occur at the site, Thompson Common has been selected as the best site for a second reintroduction.

4.2. Release location The area selected for the release of pool frogs is the southern part of NWT management compartment 6 (the eastern half of unit 2 of Thompson Water, Carr and Common SSSI) (Fig. 1). This area has been wooded probably as early as the 19th century (NWT, in prep.) and has been selected because:  This area has been recently restored (and hence currently has limited wildlife value).  It includes a high density of discrete ponds that could, with management, be favourable to pool frogs.  It has no official public access (which reduces the risk of disturbance and collection, an important factor in the early stages of reintroduction).  It is centrally located in the nature reserve, giving good potential for dispersal of pool frogs.

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Fig. 1: Area selected for the release of pool frogs indicated by red shading (base map courtesy of NWT)

4.3. Addressing extinction factors at Thompson Common A key issue for reintroductions is identifying causes of a previous extinction and removing or reducing these (IUCN, 2013 and see Appendix 2). Probable factors in the extinction of pool frogs at Thompson Common have been identified as recurrent dry summers, lowered water table, scrub encroachment, reduction in grazing pressure, and collection (Buckley & Foster, 2005). Some of these factors likely influenced each other (e.g. reduction of grazing and scrub encroachment), and acted in concert on the pool frog population.

A lowered water table, likely due to high abstraction, was identified as the probable key extinction factor (Beebee & Wycherley, 2001). The pool frog tadpole stage spans the summer months, so ponds holding water until at least mid-August are critical to pool frog populations. NWT has installed sluices on Thompson Common, which hold water on the site, countering the lowered water table.

A reduction in grazing over much of the site led to significant vegetational changes from the 1940s until quite recently, specifically a change from a relatively open grassland site to extensive scrub and secondary woodland (Gibbons, 2004; Snell, 2006, NWT, in prep.). Pool frogs require relatively open (unshaded) ponds. Increased vegetation growth has resulted in shading pingos by emergent vegetation and, eventually, scrub and trees, reducing the number of suitable ponds. It is notable that when John Buckley and John Goldsmith surveyed Thompson Common for pool frogs in 1974 they reported that the areas where they found frogs were areas that had been kept open by grazing (Buckley, 1974).

The successional changes have been reversed by a programme of clearance carried out by NWT between 1995 and 2010 (Norfolk Wildlife Trust, in prep.) which has removed large areas of scrub and secondary woodland, especially in SSSI unit 2, and has reinstated livestock grazing to maintain the Common as more open habitat.

The increased extent of open habitat and the water control measures undertaken by NWT have increased the number of ponds that are potentially suitable for pool frogs. This

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reduces the threat posed by a series of dry summers as there is a greater range of open ponds for frogs to move between in response to lowering water levels.

The threat of collection in future is difficult to quantify. Pool frogs have certainly been removed from Thompson Common in the past, which is unsurprising given the fact they were widely considered to be an introduced novelty. The extent to which this affected population status is unknown, though collection in the later stages of population decline could have hastened extinction. It is a reasonable assumption that the rarity of the northern pool frog will make it a target for theft once reintroduced, albeit probably within a limited circle of persons. The proposed release area lies within part of the nature reserve where access is by permit only. The area is also relatively distant from reserve access points. Although these factors do not entirely remove the threat of theft, they are practical and proportionate measures that reduce the risk.

Note that the intention is for pool frogs to eventually spread to other parts of the reserve. Although spread to publicly accessible areas will increase the risk of collection, by this stage the expanding population should be sufficiently robust to survive this threat. Indeed, it is a desirable outcome of the reintroduction that pool frogs should move into publicly accessible areas of the nature reserve where visitors will be able to see and hear them.

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5. Reintroduction methods

5.1. Overview The second, proposed reintroduction can be divided into three elements:  Management of habitat at Thompson Common (pre- and post-translocation).  Translocation of pool frogs from the first reintroduction site to Thompson Common.  Monitoring.

5.2. Overview – habitat management Habitat management is recognised as a critical component in successful amphibian recovery projects (Germano & Bishop, 2009; Smith & Sutherland, 2014). Recent and ongoing habitat restoration and management at Thompson Common reserve (NWT, in prep.) is favourable to northern pool frogs. Specific, further measures required for the pool frog reintroduction are relatively minor. It is, however, envisaged that some further management of ponds will be required, namely removal of silt and scraping sections of pond edge to create more open ponds. Habitat management is considered in the short- and long-term. Long-term management may have to address the issue of excessive vegetation growth within ponds as this appears to be a developing issue with consequences for both aquatic vegetation communities and pool frogs.

5.3. Overview – translocation Establishing a new population could be achieved by releasing frogs from one of two sources: individuals taken from another site in the wild (i.e. translocation), or individuals from a captive collection (i.e. release of captive-bred animals). Captive-breeding and release can be a successful method, but for the pool frog it would be prohibitively costly in order to do this to good practice and avoid the inherent risks (mainly pathogen transfer and artificial selection).

Translocations of amphibians for conservation purposes are becoming more successful as techniques, planning and implementation improve (Germano & Bishop, 2009; Germano et al, 2014; Ewen et al, 2014; Smith & Sutherland, 2014). The translocation element of the proposed reintroduction will take place over three or four years (the Breaking New Ground Project is due to finish in 2017, but Amphibian and Reptile Conservation aims to raise funds to allow an extension of pool frog releases into 2018 to allow the scope for four annual releases if monitoring indicates this is desirable). Staged introductions reduce the chances of succumbing to the adverse effects of stochastic environmental conditions (Dodd, 2010). They have become working practice for herpetofauna reintroductions carried out by The Amphibian and Reptile Conservation Trust; indeed, the first pool frog reintroduction took place over four years.

A significant difference between the currently proposed reintroduction and the methodology used in the first reintroduction is that instead of transferring stock of mixed life stages directly from one site to the other, the current proposal is to take eggs from the first, source, site grow tadpoles under captive conditions until near metamorphosis and then release them at Thompson Common. This approach, known as head-starting, is proposed because it takes advantage of the reproductive potential of amphibians to generate large numbers of individuals for release (Bloxam & Tonge, 1995) while minimising the impact of removal of stock from the donor population. Tadpoles will be head-started using techniques developed under the pool frog reintroduction programme and used successfully in 2013 (Baker, 2014b).

The reintroduction will involve the release of 600-1000 late stage larvae or metamorphs each year for three of four years. These founders will be released into a small number of ponds in compartment 6 assessed to have high habitat suitability at the time of release.

5.4. Overview – monitoring The reintroduction will be monitored (Section 9) to assess its success, to check on any adverse impacts and to allow adaptive management if necessary.

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6. Habitat management

6.1. Pre-release habitat management measures Liaison between NWT and the Pool Frog Expert Group in recent years has helped management works to improve the site considerably for pool frogs. At the time of writing, no further special habitat measures are required prior to the release of pool frogs.

The habitat management requirements of the pool frog are highly consistent with those of the site as a whole. The site Management Plan (NWT, in prep.) summarises the management challenges as the ongoing restoration of a substantial part of the reserve from woodland and scrub to open pingos and grassland, together with managing a suitable grazing regime which maintains these open conditions, whilst minimising negative impacts on the wildlife of the site. These challenges favourably encompass pool frog habitat management issues.

Site management that favours pool frogs (holding water on site and clearing trees and scrub to create an open habitat) has already been undertaken by NWT, as summarised in section 4.3. Additionally, removal of Typha by weed basket has been carried out under Natural England’s consent to NWT. This has increased the area of open water, which is also likely to favour pool frogs.

6.2. Proposed short-term habitat management measures Habitat management funding has been secured through the Breaking New Ground project (Heritage Lottery Fund and contributions from NWT). This further habitat management work on ponds within the pool frog release area will be as follows:  Scraping limited sections of pond edges to remove emergent vegetation and create sections of open pond banks;  Mechanical excavation of emergent vegetation and superficial silt layer to create open water.

At the time of writing (March 2015) it is not possible to determine which ponds will require this work. Aquatic vegetation growth and hydroperiod in the pool frog release area will be monitored over summer 2015 and ponds that require further management work will then be identified. Any further required pond work will be carried out over the winter of 2015/16 (subject to agreement and consent from Natural England).

Care will be taken to avoid ponds where Crassula helmsii has been found, to avoid spreading this non-native invasive plant. Any mechanical excavation will be preceded by core-sampling to establish the depth of recent silt deposition to ensure that only recently accumulated material is removed, and not older deposits.

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Fig. 2: Two photographs showing ponds in the pool frog release area after vegetation clearance by weed basket (February 2015).

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6.3. Proposed long-term habitat management measures The long-term management requirements of pool frogs should largely be met by measures already planned for the site as a whole under the Management Plan (NWT, in prep.). The pool frog release area should be grazed to maintain open terrestrial and aquatic habitat, which is consistent with the Management Plan specifications for parched acid grassland (no more than 10% bracken cover, no more than 5% scrub cover, average sward height 5 cm or less). Monitoring will determine whether extensive grazing measures for the site will be sufficient to maintain habitat within the reintroduction area in a condition favourable to pool frogs. If site grazing is insufficient then a specific measure for pool frogs will be to increase the grazing intensity within the pool frog reintroduction area. This will entail installing temporary or permanent stock fencing across the northern boundary to fully enclose the reintroduction area, which would allow control of livestock therein.

Historically, grazing and natural processes, especially periodic pond drying, maintained sufficient open water to provide favourable pool frog habitat at Thompson Common. Peat- cutting, marl-digging and hemp-retting have been proposed as activities that may have contributed to pond longevity (Gibbons, 2004)and at least one pond has been deepened for fish, but for the most part it appears that pingos have been maintained without human intervention. There are indications, though, that this may no longer be the case. The NVC survey (Yaxley, 2013) raises the issue of decreasing areas of open water in unshaded pingos. A similar situation has occurred at the first pool frog reintroduction site, where marked pond succession has been observed within a ten-year period, in spite of grazing pressure. At both sites it appears that grazing is effective in managing terrestrial vegetation but is insufficient to maintain pond vegetation at an early successional stage. This vegetational change and the diminishing amount of open water may be caused by diffuse pollution. For example, nitrogen deposition threatens semi-natural, nutrient-poor habitats including the eutrophication of water bodies (e.g. Emmett et al., 2011). Both Smith (2013) and Yaxley (2013) note the importance of early successional stage ponds to plant diversity and communities (NVC S1-S4). If grazing management cannot prevent pond succession then Yaxley’s (2013) proposal for occasional and very careful mechanical clearance of selected pingos should be implemented as a long-term programme within the pool frog release area. An average rate of one or two ponds per year should suffice. This will not only maintain some ponds at an early successional stage, but will also diversify the range of successional stages overall. In the Swedish range of the pool frog, conservation practitioners have noted that higher rates of pond restoration are needed to counter accelerated pond succession, apparently influenced by nitrogen deposition.

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7. Translocation and head-starting

7.1. Overview of head-starting Head-starting involves the collection of eggs from the wild, rearing them in captivity through the larval (tadpole) stage, and then releasing around the completion of metamorphosis. The rationale is that this method enhances survival by protecting larvae against the high mortality rates experienced in the wild. There is evidence from other amphibian projects that it can be a successful technique (see review in Smith & Sutherland, 2014). A head- starting methodology has been developed during the course of the pool frog reintroduction programme and has been described for in an unpublished report to Amphibian and Reptile Conservation (Baker, 2014b). Indications are that implementation of these techniques significantly increased annual productivity of the reintroduced population. Head-started individuals approximately doubled metamorph productivity in 2013, making it the second most productive year of the reintroduction. This success was followed in 2014 by the highest counts of juveniles seen at the reintroduction site (Baker, 2014a).

7.2. Collection of eggs Approximately twelve clumps of pool frog spawn will be taken from the donor site each year. Collection methods will attempt to maximise the chances of these clumps being from different females; ideally clumps will be taken from a range of locations from different ponds, and at different times over the spawning period. This should allow the release of 600-1000 late stage larvae or metamorphs per year. Locating and taking spawn will require wading into breeding ponds and possibly the use of a small rowing boat. Biosecurity risks will be minimised by adhering to biosecurity protocols (Peniche & Sainsbury, 2014) and using equipment employed during pool frog monitoring and site maintenance work. Equipment and clothing that routinely enters the water is used only at the donor site; any other equipment that may be used in the water is cleaned and sterilised prior to use at the site.

7.3. Hatching and initial growth (indoors) Spawn will be transported to the contracted surveyor’s home where hatching and the initial stages of tadpole growth will be accommodated indoors. Spawn and tadpoles will be maintained in plastic containers, in tap water inoculated with pond water taken from the donor site. This stage poses minimal biosecurity hazards because being indoors removes the risk of contact with other amphibians (no amphibians or any other animals are kept by the surveyor). When the tadpoles are free-swimming and have grown to a size that allows easy handling and transportation (at approximately two to three weeks) they will be transferred to other headstarting venues (section 7.6) where they will eventually be transferred to artificial ponds, outdoors.

7.4. Growth in artificial ponds (outdoors) Tadpoles will be reared outdoors in artificial ponds. These ponds will be similar to those used in 2013. Plasterers’ baths will be partially sunk into the ground to buffer them from temperature fluctuations. They will be filled with tap water and inoculated with pond water transported from the first reintroduction site. Aquatic vegetation taken from the first reintroduction site will be added to the artificial ponds to provide cover and a feeding substrate.

The ponds will be protected from incursions by other wild amphibians that may occur in the vicinity and potential predators (e.g. predatory water invertebrates, grass snakes and birds) by mesh covers. Tadpoles will be monitored and fed as frequently as logistics permit, ideally several times a day when the tadpoles are growing at their fastest.

7.5. Release of metamorphs Once tadpoles approach the final stages of metamorphosis, they will be transported to the release site at Thompson Common. Tadpoles grow and develop at different rates so the release will occur in stages as individual tadpoles approach the completion of the larval stage, throughout July and August. Depending on logistical considerations, they may be released either as late stage tadpoles or as metamorphs. Tadpoles will be transported in

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10-litre containers partially filled with aged tap water mixed with water from the artificial ponds and packed with aquatic vegetation from these ponds.

Each year from 2015 to 2017 (and possibly 2018 depending on monitoring results), 600- 1000 tadpoles will be released. Tadpoles will be released in a small number of ponds in compartment 6 assessed at that time to demonstrate high quality habitat. In particular, release ponds will be selected on the basis of factors likely to assist newly metamorphosed frogs, such as opportunities for basking, prey abundance and cover from predators.

7.6. Locations of artificial ponds The artificial ponds will be housed at three venues which include two zoological collections and (possibly) a private garden. Neither of the zoological collections maintains any other amphibian species, which reduces the risk of pathogen transfer during head-starting. All personnel involved in care of tadpoles will be thoroughly trained in biosecurity measures and care of tadpoles.

7.7. Managing disease and health risks A disease risk analysis, disease risk management and post-release health surveillance (McGill & Sainsbury, 2006; Vaughan & Sainsbury, 2011) have been undertaken by the Institute of Zoology as part of the pool frog reintroduction programme. The Swedish founder stock of pool frogs was screened for disease immediately prior to release into England and annual surveillance has been carried out until 2011. Amphibians already resident in the release area have also been clinically examined prior to the release of pool frogs and several times until 2011 (Vaughan & Sainsbury, 2011). Health screening has found no substantive evidence that the health of the native amphibians or the pool frogs has been significantly adversely affected by the reintroduction. Although several bacteria identified as potential pathogens have been identified (Vaughan et al., 2009), no significant infectious agents or diseases have been detected in any of the resident or introduced amphibians examined and, in particular, all surveillance for the chytrid fungus Batrachochytrium dendrobatidis and ranavirus have proved negative. The fact that reintroduced pool frogs and their progeny have reasonable survival rates, demonstrate good growth, exhibit typical behaviours, and breed regularly indicates that there is unlikely to be any significant health problem. Likewise, there is no sign of declines or poor health status in the non-introduced amphibians.

Inherently, a wild-to-wild translocation of this type carries low disease and health risks. There is no indication of amphibian diseases at either Thompson Common or any of the potential head-starting venues. A disease risk assessment of the second pool frog reintroduction is currently (March 2015) being finalised by the Institute of Zoology (Shotton & Sainsbury, 2015), and Amphibian and Reptile Conservation will submit this along with an overview of disease risk management to Natural England in late March or April 2015.

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8. Monitoring

8.1. Post-release monitoring of pool frogs Pool frogs will be monitored using methods developed during to the first reintroduction. Monitoring will occur in several phases, as follows:

 During 2015, six visits will be made following the releases, i.e. during August and September 2015, to record counts of pool frogs at the release ponds and nearby ponds.

 From 2016 onwards, monitoring will involve six survey visits during May-June to identify ponds where pool frogs are present. Where they are found, counts will be made during a single circuit of each pond. Frogs will be recorded photographically to allow individual identification. This will then allow a population estimate, survival estimate and an assessment of dispersal. Population size and survival will be estimated using annualised capture data in the capture-recapture programme MARK (or equivalent methods at the time of analysis).

 From 2017 onwards a further six visits will be made (late July-September) to determine reproductive success by counts of metamorphs. In addition, during this phase, the May-June surveys will include counts and locations of calling males, along with searching for spawn. These surveys will be continued annually until at least 2025, subject to annual review and funding availability.

The chart below summarises how key monitoring measures will progress through the reintroduction. An open box indicates that the measure is not possible or desirable, a grey box indicates a partial or early indication of the measure will be undertaken, and a black box indicates there will be a full assessment of the measure. Note that some measures will not be possible until several years after the first releases.

Monitoring measure 2015 2016 2017 2018 2019-20 Adult count (site total and per pond) Juvenile count (site total and per pond) Metamorph count (site total and per pond) Adult population estimate (site total) Adult annual survival Calling males (per pond) Successful metamorphosis (per pond) Presence (per pond) Dispersal Demographic profile

8.2. Monitoring other amphibian species Four other amphibian species (great crested newt Triturus cristatus, smooth newt Lissotriton vulgaris, common frog Rana temporaria and common toad Bufo bufo) occur at both the first release site and Thompson Common. Some baseline survey information is available for Thompson Common in recent years.

Although pool frogs were not expected to have a negative impact on these species during the first introduction, they were also monitored by annual surveys. These have been undertaken from 2004, the year prior to the first release of pool frogs, until the present (Baker, 2014c). This monitoring programme has provided data of varying levels of detail for the four target species but there has been no evidence of a negative impact of pool frogs and, on the contrary, common frogs and common toads appear to have benefited substantially, presumably from the habitat restoration and management measures carried

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out. It seems likely that the newts have also benefited although detectability issues mean that the data cannot be used to determine population trends. Newts are difficult to survey quantitatively in pingo habitats and vegetational changes affect the ease with which they can be found, so that our survey data provide information about presence/absence at the pond level, but not indications of population size or changes therein.

Given that other amphibian species appear to have benefited from the first pool frog reintroduction, monitoring these at Thompson Common for the second reintroduction is a lower priority and hence will be less intensive. The proposed programme is as follows:

 A sample of 10 survey ponds will be selected.  Two daytime/visual surveys of each pond will be made to search for and count common frog spawn clumps (Griffiths & Raper, 2004)  One daytime/visual and netting survey will be made of each pond  Habitat suitability indices for great crested newt will be carried out.  Monitoring will be undertaken in 2015 before releases, and then in 2016, 2018, 2020 and 2024.  Monitoring results will be reviewed annually and changes to the monitoring schedule assessed.

Table 2. Proposed monitoring of other amphibians and sticklebacks Target species Visual surveys Netting survey Data collected Great crested newt Eggs N/A Presence/absence Smooth newt N/A Adults Presence/absence, counts Common frog Spawn clump N/A Counts/Population size counts Common toad Adults, spawn, Tadpoles Presence/absence tadpoles Sticklebacks N/A Fry and adults Presence/absence, counts

8.3. Monitoring habitat Vegetation growth of all ponds within the pool frog reintroduction area will be monitored using fixed-point photography and estimates of the area of open water and extent of shoreline dominated by emergent vegetation in May and July. The information gathered will be used to guide future habitat management work (sections 6.2 and 6.3).

8.4. Monitoring impacts on other SSSI features Monitoring of impacts of the release of pool frogs and associated management measures will be evaluated through SSSI condition monitoring. This should be carried out to:  Determine whether unit 2 improves from currently unfavourable recovering  Compare the status of SSSI features (plant communities and invertebrates) between unit 2 and other units.

Independent surveys undertaken for other taxonomic interests at Thompson Common should be encouraged to consider the impacts of management measures within the pool frog reintroduction area. Data from other surveys supplied to NWT will be used to inform management of the pool frog reintroduction area.

8.5. Indicators of success There are two proposed levels of indicators of success, as follows.

Early indicators:  Survival of eggs and larvae through to metamorphosis  Recruitment of juveniles into adults  Breeding activity, demonstrated by egg-carrying females, calling males, amplexus, and spawning.

Long-term indicators:

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 Establishment of adult population size, within 5-10 years, in excess of 50 individuals (the minimum to avoid serious inbreeding risks), and preferably >100 adults  Mixed population structure, with juveniles and adults regularly recorded, in turn indicating regular breeding success  Progressive colonisation of multiple ponds, at least five over 5-10 years, indicating the establishment of a robust metapopulation structure.

Annual monitoring results will be assessed against these success criteria as the project develops.

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9. Regulatory compliance

9.1. Species and site legal protection Broadly speaking, there are two legal aspects to consider:  Head-starting and translocation of a protected species  Implications of impacts and potential impacts on a protected site (Thompson Common)

9.2. Head-starting and translocation of a European Protected Species The pool frog is listed on Annex IV(a) of the European Habitats Directive (Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Flora and Fauna) making it a species of European community interest in need of strict protection. This is transposed to English Law under The Conservation of Habitats and Species Regulations 2010 (as amended) (often termed the “Habitats Regulations”), which include the pool frog under Schedule 2 (European Protected Species of Animal).

To permit taking eggs, possessing tadpoles and releasing tadpoles or metamorphs at a site other than the site of origin will require a licence from the relevant licensing authority, Natural England. Natural England can licence these activities for the purpose of conserving wild animals or wild plants or introducing them to particular areas (Regulation 53[2c]). Preliminary communication with Natural England (Corrie Bruemmer) has established that the licence application should be supported by a reintroduction proposal that:  Follows IUCN reintroduction guidelines;  Provides reasoning for why Thompson Common has been selected as the release site;  Is supported by a disease risk assessment.

The licence is applied for using form WML A29, and turn-around time for a decision is 30 days. The current document constitutes the project managers’ evidence to demonstrate that the licensable activities and related reintroduction plans follow IUCN reintroduction guidelines and other pertinent good practice. This document can also be viewed as a Method Statement for the licence application. Furthermore, it summarises why Thompson Common has been selected as the reintroduction site (see section 4.1), and outlines the approach to disease risk assessment. Additional information on disease risk assessment will be provided shortly after licence submission.

9.3. Implications of impacts and potential impacts on a protected site Thompson Common is part of Thompson Water, Carr and Common Site of Special Scientific Interest. SSSIs are notified under section 28(1) of the WCA 1981 as substituted by Schedule 9 to the Countryside and Rights of Way Act 2000, which protects biological and/or geological features. Protection is implemented by a consultation and consenting process, regulating operations that are likely to harm the site’s features of interest.

Thompson Common also has a European designation, as part of the Norfolk Valley Fens Special Area of Conservation (SAC). SACs are designated to protect the best examples of endangered habitats and species listed under Annex II of the Habitats Directive (Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora). This forms an additional layer of protection to the SSSI status, but interest features of both are listed within the Favourable Condition Table for the Site. Activities that are not directly connected with or necessary to the management of the site that may affect it are subject to an Appropriate Assessment. This is transposed to British law by the Conservation of Habitats & Species Regulations 2010 (as amended).

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10. Impact of reintroduction on SSSI/SAC features

10.1. Consistency with Views About Management As part of the SSSI notification process a Views About Management statement is provided by Natural England to describes the management needed to conserve and enhance the features of the SSSI. The statement for Thompson Common (English Nature, 2005) provides information for the grassland, wetland and woodland habitats and great crested newts. This information is rather generic. The habitat management proposed for the second reintroduction is consistent with the majority of the statement. For example, grazing proposed here is consistent with active management considered in the statement as essential to the management of grassland habitats.

The only potential notable difference between the two regards pond management. The Views About Management do not refer specifically to pingos but do advise that springs and spring-fed pools should be allowed to maintain their natural profiles and should not be physically modified. The proposed management does not include measures to alter pingo profiles but it does recommend a programme of restoration to maintain ponds at range of successional stages. This entails removal of silt and vegetation, which might be regarded as physical modification, depending on interpretation. Nevertheless, the management proposed in this document is intended to remove superficial debris only, and not alter natural pond profiles. Therefore, it is reasonable to conclude that the methods proposed here are not in conflict with the site’s Views About Management. The rationale for this intervention is given in section 6.3.

10.2. Operations requiring consent Natural England produces a list of operations likely to damage interest features for each SSSI, and a consent is required to undertake these lawfully. The operations regarded as likely to damage features at Thompson Water, Carr and Common SSSI are listed in Table 3. The pool frog reintroduction and associated habitat management include operations 2, 9 and 11 (highlighted in Table 3) which therefore require consent from Natural England. Consideration of each follows:

“2. The introduction of grazing and changes in the grazing regime (including type of stock or intensity or seasonal pattern of grazing and cessation of grazing)” Grazing is already in place as a site management method (NWT, in prep.). This is consistent with management requirements for pool frogs although the reintroduction requires the option to increase grazing intensity above that being applied to the site as a whole. If this is required then additional stock-fencing will be needed to partition off the pool frog reintroduction area. Installation of stock- fencing should have a negligible impact on features of interest if done sensitively. More intensive grazing will have an effect on vegetation but its impact should be favourable, maintaining ponds at earlier stages of succession and diversifying successional stages at the site level.

“9. The release into the site of any wild, feral or domestic animal, plant or seed” The pool frogs themselves are unlikely to have any significant negative impact on existing site features (Table 5). They were formerly an integral part of the site and are still listed in the SSSI citation.

“11. The destruction, displacement, removal or cutting of any plant or plant remains, including tree, shrub, herb, hedge, dead or decaying wood, moss, lichen, fungus, leaf-mould or turf” The proposed long-term mechanical intervention to manage ponds (section 6.3) is such an operation. In practice, however, this intervention should have a positive effect both for pool frogs and in maintaining more open ponds (discussed in section 6.3). The overall impact of this will be to diversify the range of successional stages within the pool frog reintroduction area and the reserve as a whole.

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Table 3. Operations likely to damage the interest features of Thompson Common (www.sssi.naturalengland.org.uk/Special/sssi/old/OLD1000249.pdf)

1 Cultivation, including ploughing, rotovating, harrowing, and re-seeding. 2 The introduction of grazing and changes in the grazing regime (including type of stock or intensity or seasonal pattern of grazing and cessation of grazing). 3 The introduction of stock feeding and changes in stock feeding practice. 4 The introduction of mowing or other methods of cutting vegetation and changes in the mowing or cutting regime (including hay making to silage and cessation). 5 Application of manure, fertilisers and lime. 6 Application of pesticides, including herbicides (weedkillers). 7 Dumping, spreading or discharge of any materials. 8 Burning. 9 The release into the site of any wild, feral or domestic animal, plant or seed. 10 The killing or removal of any wild animal, excluding pest control. 11 The destruction, displacement, removal or cutting of any plant or plant remains, including tree, shrub, herb, hedge, dead or decaying wood, moss, lichen, fungus, leaf- mould or turf. 12 The introduction of and changes in tree and/or woodland management (including afforestation, planting, clear and selective felling, thinning, coppicing, modification of the stand or underwood, changes in species composition, cessation of management). 13a Drainage (including gripping and the use of mole, tile, tunnel or other artificial drains). 13b Modification of the structure of watercourses (eg streams, springs, ditches, dykes, drains), including their banks and beds, as by re-alignment, re-grading and dredging. 13c Management of aquatic and bank vegetation for drainage purposes. 14 The changing of water levels and tables and water utilisation (including irrigation, storage and abstraction from existing water bodies and through boreholes). 15 Infilling of ditches, dykes, drains, ponds, pools, marshes or pits. 16a The introduction of or changes in freshwater fishery production and/or management, including sporting, fishing and angling. 20 Extraction of minerals, including peat, sand and gravel, topsoil, subsoil, and chalk. 21 Construction, removal or destruction of roads, tracks, walls, fences, hardstands, banks, ditches or other earthworks, or the laying, maintenance or removal of pipelines and cables, above or below ground. 22 Storage of materials. 23 Erection of permanent or temporary structures, or the undertaking of engineering works, including drilling. 24 Modification of natural or man-made features including infilling of pits. 26 Use of vehicles or craft likely to damage or disturb features of interest. 27 Recreational or other activities likely to damage features of interest. 28 Introduction of and changes in game and waterfowl management and hunting practice. Highlighting = operations relevant to the current reintroduction plan.

10.3. Avoidance of designated features Most of the features for which Thompson Water, Carr and Common are designated occur within SSSI unit 2. Management measures proposed here will take care to avoid these features.

The only NVC listed feature that occurs in the proposed pool frog reintroduction area is S1 Carex elata swamp (Fig. 2). This readily identifiable community will be located prior to any further management so that work can avoid the Carex elata tussocks.

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Fig. 3: Wetland NVC communities taken from Yaxley (2013).

Table 4. Ponds within proposed pool frog area and listed features present. Pond Code Interest feature 37 355 6A 41 355 6E Ricciocarpus natans 57 355 7B Ricciocarpus natans 58 355 7A S1 Carex elata swamp 59 355 7C 60 365 7A 61 365 7B 62 365 7C Ricciocarpus natans 63 365 8A* 64 365 8A* 67 355 8A 68 355 8B S1 Carex elata swamp, Ricciocarpus natans *63 and 64 have the same reference code.

10.4. Risk of harm to designated features Notable species occur within the pool frog reintroduction area. The liverwort Ricciocarpus natans (a Red Data Book Species) has been found in four ponds within the pool frog reintroduction area, but it also seems relatively common throughout the reserve, present in 30 out of 130 ponds surveyed recently (Smith, 2013). Pond restoration will take into account the presence of interest species as far as practically possible. Data held by NWT will be examined prior to any planned mechanical pond management work. Interest plant locations will be avoided by mechanical management and ponds supporting invertebrates that are found nowhere else within the reserve will not be disturbed. It may not, however, be practical to confine mechanical management only to ponds that do not support significant species. Many aquatic invertebrates rapidly colonise new ponds and hence interest species are likely to occur in ponds within the pool frog reintroduction area in spite

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of the fact that restoration has been only recent. Overall, pool frog reintroduction activities should not harm designated features so long as reasonable precautions are taken.

10.5. Reintroduction site benefits The reintroduction of the pool frog to Thompson Common and the associated habitat management measures will have benefits, which should not be overlooked. The re- establishment of the northern pool frog itself will contribute to the conservation objectives of the site. The habitat management measures associated with the reintroduction are also necessary to the management of the site and to avoid its deterioration.

The pool frog’s presence at Thompson Common was dependent on the habitat conditions that also make it such a significant pond site. Hence, management measures for pool frogs will act as an umbrella for plants, invertebrates and other amphibians dependent on the same habitat. Experience from the first reintroduction site indicates that habitat restoration and management for pool frogs has provided a high quality pond network benefiting a diverse range of aquatic and terrestrial flora and fauna.

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Table 5. Risks to site interest features based on Table 1 of the Favourable Condition Table for Thompson Water, Carr and Common SSSI/SAC Individual designated Specific designated Explanatory SSSI SAC Risk posed by pool frog reintroduction interest features BAP features description of the Broad Habitat Type feature for clarification Fen, Marsh and Swamp Alkaline fens Mire * No risk. Sub-community M9b does not occur within the M9 Carex rostrata- proposed pool frog reintroduction area (Yaxley, 2013). Calliergon cuspidatum/giganteum mire SSSI Swamp * * No risk. Sub-community S2a does not occur within the S2 Cladium mariscus swamp proposed pool frog reintroduction area (Yaxley, 2013). and sedge-beds SAC Calcareous fens with Cladium mariscus and species of the Caricion davallianae S1 Carex elata sedge- Swamp * Minimal risk. This community occurs in three stands swamp within the proposed pool frog reintroduction area. Any pond management measures can be planned to avoid these stands. S3 Carex paniculata sedge- Swamp * No risk. Sub-community S3 does not occur within the swamp proposed pool frog reintroduction area (Yaxley, 2013). S4 Phragmites australis Swamp * No risk. Sub-community S4a does not occur within the swamp and reed-beds proposed pool frog reintroduction area (Yaxley, 2013). S25 Phragmites australis- Tall-herb fen * No risk. Not found in the most recent NVC survey and Eupatorium cannabinum formerly present only in compartment 19 (Yaxley, 2013). tall-herb fen S27 Carex rostrata- Tall-herb fen * No risk. Sub-community S27b does not occur within the Potentilla palustris tall-herb proposed pool frog reintroduction area (Yaxley, 2013). fen

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Individual designated Specific designated Explanatory SSSI SAC Risk posed by pool frog reintroduction interest features BAP features description of the Broad Habitat Type feature for clarification M9b Carex rostrata- Although not in the No risk. Two isolated stands were found in unit 2 but Calliergon cuspidatum mire, FCT, this community both within management compartment 7. Carex diandra-Calliergon was identified by giganteum. Yaxley (2013) and should be considered for inclusion as an interest feature. M22 Juncus subnodulosus- Fen meadow * No risk. Sub-communities M22a and c do not occur Cirsium palustre fen within the proposed pool frog reintroduction area (Yaxley, meadow 2013). Vertigo moulinsiana Desmoulin’s whorl * Some risk. This species is widespread on Thompson snail Common and present in virtually all pingos which have relatively permanent water with tall fen communities (NWT, in prep.). Although a SAC feature, its ubiquity within the reserve provides reassurance that no specific part of the site is critical for its continued survival. Hence, proposed management is unlikely to harm its long-term prospects here.

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Individual designated Specific designated Explanatory SSSI SAC Risk posed by pool frog reintroduction interest features BAP features description of the Broad Habitat Type feature for clarification Vascular Plant Assemblage: Plant assemblage: * Minimal risk. Much of the wetland area within the Calamagrostis stricta Narrow small reed proposed pool frog reintroduction area is dominated by Carex appropinquata Fibrous tussock sedge M23 Juncus effusus-Galium palustre rush pasture which Cicuta virosa Cowbane comprises a species-poor acidiophilus sward. Peucedanum palustre Milk parsley Calamagrostis stricta has been found in only one pingo, Potamogeton coloratus Fen pondweed (3663a) which is outside the proposed pool frog Thelypteris palustris Marsh fern reintroduction area (NWT, in prep.). Carex appropinquata has been found only in pingos 3663a, 3357a both of which are outside the proposed pool frog management area (Smith, 2013). There are no recent records of Circuta virosa. Peucedanum palustre and Thelypteris palustris have been found in 3562a which lies outside the proposed pool frog reintroduction area but they have also been found in C6 and elsewhere (NWT, in prep.). Proposed management measures will take into account the further discovery of any listed plant species and avoid these. Invertebrate assemblage Invertebrate * Minimal risk. Although pool frogs feed on invertebrates (see Criteria Sheet for list of assemblage they are unselective and are hence unlikely to harm species) particular species within the invertebrate assemblage. Broad Assemblage Type: Invertebrates can rapidly colonise new habitat and they W31 permanent wet mire can be found in ponds with little botanical importance. (957) and W22 litter-rich Hence notable invertebrate species are likely to occur in fluctuating wetland (138) ponds within the pool frog reintroduction area. Proposed Specific Assemblage habitat management will create relatively open ponds Types: which will diversify the site’s overall pond stock and this W221 undisturbed will support invertebrate diversity. fluctuating marsh (36) W313 mesotrophic fen (45)

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Individual designated Specific designated Explanatory SSSI SAC Risk posed by pool frog reintroduction interest features BAP features description of the Broad Habitat Type feature for clarification Broadleaved, Mixed and SSSI Alder woodland * * No risk. There is no woodland within the proposed pool Yew Woodland W5 Alnus glutinosa-Carex frog reintroduction area (Yaxley, 2013) except for a few paniculata wet woodland remaining, scattered trees. SAC Alluvial forests with Alnus glutinosa and Fraxinus excelsior. SSSI Alder woodland * * No risk. There is no woodland within the proposed pool W6 Alnus glutinosa-Urtica frog reintroduction area (Yaxley, 2013) except for a few dioica wet woodland remaining, scattered trees. SAC Alluvial forests with Alnus glutinosa and Fraxinus excelsior. Lowland Calcareous CG2 Festuca ovina- Chalk grassland * * No risk. Does not occur within the proposed pool frog Grassland Avenula pratensis reintroduction area (Yaxley, 2013). grassland

Lowland Acid Grassland U1 Festuca ovina-Agrostis Acid grassland * No risk. Most of the terrestrial habitat within the capillaries-Rumex proposed pool frog reintroduction area has been mapped acetosella grassland as U1 (Yaxley, 2013) most likely developing into U1 b (Yaxley, pers. comm.). Proposed grazing is consistent with management of acid grassland (e.g. NWT, in prep.). Standing Open Water and Natural eutrophic lakes with Thompson Water * No risk. Thompson Water lies outside the pool frog Canals Magnopotamion or reintroduction area. Hydrocharition type vegetation

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Individual designated Specific designated Explanatory SSSI SAC Risk posed by pool frog reintroduction interest features BAP features description of the Broad Habitat Type feature for clarification Ground-ice depressions Numerous shallow, * Minimal risk. Pool frogs are dependent on a network of (pingos) usually water-filled relatively open, well-insolated ponds. Proposed pond depressions, often management measures to achieve this are likely to benefit the site by increasing diversity at two levels. surrounded by a Proposed habitat management will maintain relatively rampart. open ponds which will diversify the site’s overall pond stock. Triturus cristatus Great crested newt * Minimal risk. Pool frogs pose no direct threat to great crested newts. Monitoring at the initial reintroduction site has shown no negative impacts on great crested newts. Translocation creates a risk of disease transmission but this has been minimised through risk assessments and repeated health screening which has found no evidence of significant pathogens among translocated pool frogs or other amphibians at the initial reintroduction site. Amphibian assemblage: Amphibian * Minimal risk. Pond conditions favoured by these species Triturus cristatus assemblage: overlap with pool frog requirements. Monitoring these Triturus vulgaris Great crested newt species at the initial reintroduction site has shown no negative impacts of pool frogs. Biosecurity risks have Rana temporaria Smooth newt been minimised through risk assessments and repeated Bufo bufo Common frog health screening has found no evidence of significant Common toad pathogens among translocated pool frogs or other amphibians at the initial reintroduction site.

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Individual designated Specific designated Explanatory SSSI SAC Risk posed by pool frog reintroduction interest features BAP features description of the Broad Habitat Type feature for clarification Mixed assemblage (open Assemblage of * Generally no risk. Conversely, amphibians provide prey water, woodland): breeding birds: to many bird species. Any additional pond management Fulica atra Coot will be timed to avoid nesting birds. An exception is grey heron; measures to reduce risk of Anas strepera Gadwall predation by herons on young pool frogs in the early Podiceps cristatus Great crested grebe stages of reintroduction may be required. Ardea cinerea Grey heron Anas platyrhynchos Mallard Aythya ferina Pochard Tringa totanus Redshank Acrocephalus scirpaceus Reed warbler Charadrius hiaticula Ringed plover Anas clypeata Shoveler Gallinago gallinago Snipe Anas crecca Teal Aythya fuligula Tufted duck Anas penelope Wigeon

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10.6. Habitats Regulations Assessment Article 6 of the EC Habitats Directive determines the need to manage and avoid deterioration and harm to SACs. Activities that are not directly connected with or necessary to the management of the site that may affect it are subject to an Appropriate Assessment (a Habitats Regulations Assessment). Information required by Natural England to make this assessment is contained in this report, and summarised in this section.

Consent may be granted if the proposed project will not adversely affect the integrity of the site (Provision 21(2)). Recorded observations and archived specimens indicate that the northern pool frog has been present in the Thompson Common area since at least the 1850s. It appears to be part of a glacial relict fauna and so is an integral feature of the site in its own right. Translocation to reintroduce the northern pool frog to Thompson Common will not, in itself, adversely affect the integrity of the site. Conversely, reintroduction will enhance site integrity.

There is a high degree of overlap between ideal management for the reserve and pool frog habitat requirements. The habitat management measures recommended as part of the pool frog reintroduction are connected with management of the site (hence not requiring a Habitat Regulations Assessment). However, given that the pool frog reintroduction may require habitat management measures additional to those that would otherwise take place, namely an increased intensity of grazing and mechanical intervention to manage ponds, then consideration of the potential effects is a precautionary measure.

Increased grazing intensity within the pool frog release area is unlikely to harm the integrity of the SAC. Grazing is prescribed in the Management Plan to maintain acid grassland and its impact on ponds is likely to be beneficial, preventing excessive vegetation growth and overall increasing the diversity of the pond stock within the SAC.

Mechanical intervention will avoid site interest features as far as possible. Significant vegetation communities can be avoided (indeed, they are mostly absent from the pool frog reintroduction area) and all available survey information will be used to ensure avoidance of species that are site interest features. Nevertheless, it is highly likely that significant plant and animal species will be present in some ponds where mechanical intervention may be required within the pool frog release area. Several lines of reasoning support mechanical intervention:

 It is a measure that may be needed to avoid deterioration of the site (section 6.3).  Although the species in question may be notable locally or nationally, they are likely to occur in many ponds within the SAC.  The pool frog release area is only a small proportion of the site, so any negative impacts will be confined to a small proportion (less than 3%) of the ponds within the SAC.  Maintaining ponds within the pool frog reintroduction area at an early successional stage will be beneficial in diversifying the nature of ponds within the SAC.

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11. Communications

11.1. Communications strategy under the first reintroduction The proposed second reintroduction includes a communications strategy consistent with IUCN reintroduction guidance to make information available in a timely and suitable fashion to target audiences (IUCN/SSC, 2013). This has already been put into practice during the first reintroduction, and examples of these communications to different target groups are given in table 6.

Table 6. Examples of dissemination of information for the first reintroduction Target audience Examples of information dissemination Public, local Presentation by Forestry Commission to the local community. Public, general Press releases in Sweden and England. Resulting media coverage included radio, television, print and digital. Website information (primarily ARC) and material such as leaflets. Specialist and Reintroduction Strategy published by Natural England. scientific Updates in Wildlife Reports section of British Wildlife magazine. Conference presentations including the World Congress of Herpetology 2005 in Stellenbosch, South Africa, and 2012 in Vancouver, Canada, Herpetofauna Workers Meetings and the West Midlands ARG UK Conference (2013). Peer-reviewed papers summarising the results of the reintroduction and the disease risk management issues are in preparation. Supplementary aspects of monitoring work have been published e.g.: Baker (2010). Hydrophilus piceus in West Norfolk. Latissimus 27, 30. Baker (2012). Pelophylax lessonae (Pool Frog). Predation and reintroduction. Herpetological Review 43(2), 324. Baker (2013). Effect of bait in funnel-trapping for great crested and smooth newts Triturus cristatus and Lissotriton vulgaris. The Herpetological Bulletin 124, 17-20. Sewell, D., Baker, J.M.R. & Richard A. Griffiths, R.A. (in press). Population dynamics of grass snakes (Natrix natrix) at a site restored for amphibian reintroduction. The Herpetological Journal 25,155-161 Forman, D., Gleed-Owen, C. & Baker, J. (2012). Pelophylax lessonae (pool frog): predation by Eurasian otter Lutra lutra. The Herpetological Bulletin 119, 36-37. Statutory Reintroduction Strategy published by Natural England. All project work has been carried out under licence where necessary; proposals and results have been provided to Natural England. Partners The Pool Frog Expert Group, which oversees the reintroduction programme, is a successful partnership with representatives from the scientific, voluntary, statutory and non-governmental sectors (it includes land owners and managers from both the proposed donor and receptor sites of the second reintroduction). This group meets twice a year and results from project monitoring work are provided to this group.

The Reintroduction Strategy determined that several aspects of the initial reintroduction should be strictly confidential. The site location and details of survey methodology have been kept confidential to minimise several risks, primarily disturbance and theft of frogs, and transmission of pathogens. Communications for the first reintroduction therefore balanced dissemination of information with the need to maintain security of the introduced population. Safeguarding the population was prioritised over any communications that might reveal the precise location.

11.2. Planned communications for the second reintroduction Information about the second reintroduction will be communicated widely to specialist and non- specialist audiences. The broad aim of this communication would be to publicise the positive step towards recovery of the pool frog in the UK. Communications will ensure acknowledgement of all partners and funding, in particular the significant contribution of the Heritage Lottery Fund via the Breaking New Group project. Communications tailored to different target audiences are given in Table 7.

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The second reintroduction will inherently serve to reduce the magnitude of potential harm posed by the threats mentioned above. Having two reintroduced populations at geographically separate sites means that if one were harmed then the other site provides a degree of security for the species overall. Although there remains a risk that pool frogs may be subject to theft or disturbance once the site location is announced, the fact that the release area is closed to public access means the risk is low. Site staff will be asked to remain vigilant for unauthorised attempts to reach the pool frogs. After considering the risks and benefits, it is considered that the location of the second reintroduction site should be made public, in contrast to the first site (which will continue to remain confidential). Such a position gives greater scope for communications.

Table 7. Dissemination of information for the second reintroduction Target audience Examples of information dissemination Public, local Thompson Water Fishing club will be advised of the hazards of release of non- native species (especially water frogs). The potential to link messages to ongoing problems caused by the introduction of water solider will be investigated. Public, general A publicity event will be organised in conjunction with the release of froglets at Thompson Common, to publicise the reintroduction. Interpretation material (information leaflets and an interpretation board) will be produced for Thompson Common. The reintroduction project will make links with zoological collections to develop interpretative material (section 11.2). Specialist and Project summary and monitoring information will be published to add to the scientific relatively limited data on amphibian introductions. Other information gleaned during monitoring work will continue to be published. Project information will be presented at scientific and other specialist conferences as opportunities arise. Statutory Natural England is a project partner and will continue to be informed of progress via the Pool Frog Expert Group, licence returns and routine liaison. Partners The Pool Frog Expert Group will continue to meet twice a year to allow partner liaison. Monitoring data will continue to inform this group of project progress.

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12. Engagement with zoological collections

12.1. ‘Hybrid’ pool frogs in zoological collections During the course of the first reintroduction, some zoological collections have bred pool frogs descended from crossing the last known English native pool frog with frogs from a mixed English- Netherlands descent. These ‘hybrid’ pool frogs have been passed between collections. This captive breeding has been carried out independently of the reintroduction programme and there are no plans to release these frogs into the wild, which would be unwise given their genetic identity. Nevertheless, there is a risk of deliberate or accidental release into the wild via unofficial movement of stock between individuals. The establishment of ‘hybrid’ populations in the wild would, at least, be potentially confusing and, at worst, could genetically contaminate and undermine the reintroduction of the northern pool frog. Therefore the situation with captive hybrid frogs should be improved.

12.2. Supply of northern pool frogs to zoological collections The second pool frog reintroduction will reduce the risks posed by captive breeding frogs of mixed genetic stock by engaging with the zoological collections involved. The latter will be discouraged from maintaining and breeding ‘hybrid’ pool frogs and instead will be supplied with a small number of metamorphs from the head-starting element of the currently proposed reintroduction. Neither these frogs nor subsequent captive-bred descendants will be used as a source of reintroduction stock. This is due primarily to biosecurity risks (e.g. Winters et al., 2014), but also because of the potential for adverse genetic changes in captive stock (e.g. Kraaijeveld-Smit et al. 2006). Captive frogs will, instead, be used as educational exhibits and the zoological collections will be encouraged to develop interpretative material consistent with the aims of the reintroduction project. One key benefit would be to provide the public with an accessible place to reliably observe pool frogs, given that the first reintroduction site is confidential and the release area at the second reintroduction site is closed to public access.

Captive pool frogs will be maintained under suitable conditions and following good practice as agreed by the Pool Frog Expert Group.

12.3. Legal and contractual regulation of captive stock Transfer of a small number of tadpoles or froglets from the head-starting programme into zoological collections will need to be covered by a licence. Legal protection of the pool frog under the Conservation of Habitats and Species Regulations 2010 (see section 9.2) allows possession of northern pool frogs only if licensed by the relevant body (Natural England). The licence application form is WML A29, the same as required for head-starting. Nevertheless, separate licences will be sought for each transfer of pool frog tadpoles or froglets to zoological collections; it is most appropriate for each collection to apply individually since they will be legally responsible for adhering to the terms of the licence.

The captive frogs will be owned by Natural England and the pool frogs will be loaned to selected zoological collections under written agreements that will specify that the frogs and any progeny will not be released or transferred to other parties without consent (Appendix 3). The loan agreements are an important element, as they will regulate the possession and transfer of progeny that fall outside licensing control (captive-bred stock is exempt from legal protection, which covers wild animals only). Similar arrangements have been used to manage captive stock for the Sand Lizard Recovery Programme.

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13. Acknowledgements A range of people have assisted with this document, for which the authors are most grateful. The authors would like to thank the following in particular: John Buckley (Amphibian and Reptile Conservation), Bev Nichols and Corrie Bruemmer (Natural England), Darrell Stevens, John Milton and John Hiskett (Norfolk Wildlife Trust), Justine Shotton and Tony Sainsbury (Institute of Zoology), Robert Yaxley (Wild Frontier Ecology) and the Pool Frog Expert Group. The authors acknowledge the generous contribution of the Heritage Lottery Fund via the Breaking New Ground project.

14. Literature

Baker, J. (2012). Review of secondary reintroduction sites for the pool frog. Unpublished, confidential report for Amphibian and Reptile Conservation. Baker, J.M.R. (2014a). Pool frog post-release monitoring: Pool Frog Site 2014. Unpublished, confidential report for Amphibian and Reptile Conservation. Baker, J. (2014b). Pool frog headstarting 2013. Unpublished, confidential report for Amphibian and Reptile Conservation. Baker, J.M.R. (2014c). Amphibian Survey: Pool Frog Site 2014. Unpublished, confidential report for Amphibian and Reptile Conservation. Beebee T.J.C. & Wycherley, J.T. (2001). An assessment of pool frog habitats and reintroduction prospects in Britain. Unpublished confidential report to English Nature. Beebee, T.J.C, Buckley, J., Evans, I., Foster, J.P., Gent, A.H., Gleed-Owen, C.P., Kelly, G., Rowe, G., Snell, C., Wycherley, J.T. and Zeisset, I. (2005). Neglected native or undesirable alien? Resolution of a conservation dilemma concerning the pool frog Rana lessonae. Biodiversity and Conservation 14, 1607-1626. Bloxam, Q.M.C., & Tonge, S.J. (1995). Amphibians – suitable candidates for breeding-release programmes. Biodiversity and Conservation 4, 636-644. Buckley, J. (1974). Thompson Common with notes on the distribution of the edible frog Rana esculenta in Norfolk. Unpublished report to the Nature Conservancy Council. Buckley, J. & Foster, J. (2005). Reintroduction strategy for the pool frog Rana lessonae in England. English Nature Research Report 642. English Nature, Peterborough. Defra (2011). Biodiversity 2020: A strategy for England’s wildlife and ecosystem services. Department for Environment, Food and Rural Affairs. Dodd, C.K., Jr. (2010). Conservation Management. In: Amphibian Ecology and Conservation. A Handbook of Techniques. Ed. C. Kenneth Dodd, Jr. pp. 507-527. Oxford University Press, Oxford. Emmett, B.A., Rowe, E.C., Stevens, C.J., Gowing, D.J., Henrys, P.A., Maskell, L.C. & Smart, S.M. (2011). Interpretation of evidence of nitrogen impacts on vegetation in relation to UK biodiversity objectives. JNCC Report, No. 449. JNCC, Peterborough. English Nature (2005). Views about management. A statement of English Nature’s views about the management of Thompson Water, Carr and Common Site of Special Scientific Interest (SSSI). Version date: 06/10/05. English Nature. Ewen, J.G., Soorae, P.S. & Canessa, S. (2014). Reintroduction objectives, decisions and outcomes: global perspectives from the herpetofauna. Animal Conservation, 17: 74–81. Germano, J.M. & Bishop, P.J. (2009). Suitability of amphibians and reptiles for translocation. Conservation Biology 23, 7-15. Germano, J., Ewen, J. G., Mushinsky, H., McCoy, E., & Ortiz‐Catedral, L. (2014). Moving towards greater success in translocations: recent advances from the herpetofauna. Animal Conservation, 17(S1), 1-3. Gibbons, B. (2004). Reserve Focus: Thompson Common Nature Reserve, Norfolk. British Wildlife 15(4), 240-243. Griffiths, R.A. & Raper, S.J. (1994). How many clumps are there in a mass of frog spawn? The British Herpetological Society Bulletin 50, 14-17. IUCN (1995) Guidelines for Re-introductions. IUCN/SSC Re-introduction specialist group, Gland, Switzerland. IUCN/SSC (2013). Guidelines for Reintroductions and Other Conservation Translocations. Version 1.0. Gland, Switzerland: IUCN Species Survival Commission.

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Kraaijeveld-Smit, F.J.L., Griffiths, R.A., Moore, R.D. & Beebee, T.J.C. (2006). Captive breeding and the fitness of reintroduced species: a test of the responses to predators in a threatened amphibian. Journal of Applied Ecology 43, 360-365. McGill, I. & Sainsbury, A.W. (2006) Health and welfare monitoring of the pool frog (Rana lessonae): Methods of health and welfare monitoring. London, Institute of Zoology, Zoological Society of London. McLean, I.F.G. (2003). A policy for conservation translocations of species in Britain. Joint Nature Conservation Committee, Peterborough. Norfolk Wildlife Trust (in prep.). Thompson Common Management Plan 2014-2018. Norfolk Wildlife Trust. Peniche, G. & Sainsbury, T. (2014). Pool frog (Pelophylax lessonae) reintroduction project: Disease risk management & post-release health surveillance protocol 2014/2015. Unpublished confidential report, Institute of Zoology, Zoological Society of London. Shotton, J. & Sainsbury, T. (2015). Pool frog (Pelophylax lessonae) reintroduction project: Disease risk management & post-release health surveillance protocol 2015. Unpublished confidential report, Institute of Zoology, Zoological Society of London. Smith, E. (2013). The role of active management in conserving pond diversity. Unpublished MSc thesis, University College London. Smith, R.K. and Sutherland, W.J. (2014). Amphibian conservation: Global evidence for the effects of interventions. Exeter, Pelagic Publishing. Snell, C.A. (2006). Genetic and ecological investigations of European populations of the pool frog, Rana lessonae (Camerano, 1982), with allied, osteological and species identification methods. Unpubl. Thesis, University of Greenwich. Vaughan, R. & Sainsbury, A. (2011). Disease risk management and post-release health surveillance of the pool frog (Pelophylax lessonae) reintroduction programme 2011. Unpublished confidential report, Institute of Zoology, Zoological Society of London. Vaughan, R., Molenaar, F. & Sainsbury, T. (2009). Disease risk management and post-release health surveillance of the pool frog (Rana lessonae) reintroduction programme 2009. Unpublished confidential report, Institute of Zoology, Zoological Society of London. Williams, C. & Griffiths, R.A. (2004). A population viability analysis for the reintroduction of the pool frog (Rana lessonae) in Britain. English Nature Research Report 585. English Nature, Peterborough. Wolley J. (1847). Is the edible frog a true native of Britain? Zoologist 5: 1821-1822. Winters, H.D., Albertini, K.M., Neely, L.E. & Takahashi, M.K. (2014). Prevalence of the amphibian chytrid fungus among zoos and pet store collections in the Northeastern United States. Herpetological Review 45(2), 242-244. Yaxley, R. (2013). Thompson Water, Carr and Common SSSI. NVC Survey 2013. Wild Frontier Ecology, Fakenham.

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Appendix 1. Steps required for successful implementation

This table sets out key steps needed for the second reintroduction, focusing on the initial procedural and regulatory activities in 2015. Key: JBa = John Baker; IoZ = Institute of Zoology.

Activity Personnel Date Status Submission of head-starting methodology to Institute of Zoology ARC/JBa December 2014 Completed Completion of disease risk assessment IoZ Jan-Feb 2015 Ongoing Site meeting with NE to discuss/review reintroduction plan ARC/NWT/NE Early February 2015 Completed Production of reintroduction plan JBa/ARC October 2014-March 2015 Completed Submission of application (form WML A29) for NE ‘head-starting and release licence’ to Natural ARC/JBa Mar 2015 Completed England Completion of Appropriate Assessment NE March 2015 Ongoing Submission of report on progress with management work at Thompson Common JBa March 2015 Completed Submission by ARC to NE on disease risk assessment, as additional material for licence application ARC March-April 2015 Planned Submission of note on status of head-starting facilities JBa March 2015 Planned Implementation of baseline amphibian survey at Thompson Common ARC/JBa March-June 2015 Ongoing Issue of licence to take eggs for head-starting and second reintroduction NE April 2015 (Planned) Health surveillance of amphibians at donor site (if appropriate following disease risk assessment) IoZ/ARC April-June 2015 (Planned) Health surveillance of pool frogs at first reintroduction site (if appropriate following disease risk IoZ/ARC April-June 2015 (Planned) assessment) Collection of pool frog eggs from first reintroduction site ARC/JBa May-June 2015 Planned Submission of application to NE to license transfer of limited head-started stock to zoological collections ARC/JBa May-June 2015 Planned Hatching and rearing of early tadpoles stages ARC/JBa Mid June 2015 Planned Relocation of tadpoles to secure outdoor ponds ARC/JBa Late June 2015 Planned Staged release of metamorphs ARC/JBa July-August 2015 Planned

Pool frog egg collection, head-starting and release; monitoring; habitat management as required; ARC/NWT/JBa 2016-2018 Planned reporting.

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Appendix 2. Evaluation against IUCN Reintroduction Guidelines Annexes 3-9 of Guidelines for Reintroductions and Other Conservation Translocations (IUCN/SSC, 2013), commonly abbreviated as “the IUCN reintroduction guidelines,” have been reproduced in this appendix, in italics in the left-hand column of the table below. Text in the right-hand column explains how the second reintroduction of the pool frog addresses each point.

Annex 3. Deciding when translocation is an acceptable option Annex 3.1 Introduction 1. Any proposed species translocation should be The northern pool frog is present at only a single justified by identifying a conservation benefit and site in England and, due to its specific habitat weighing any benefits against risks, while requirements, is unlikely to spread to other sites considering alternative actions that could be unaided. Translocating pool frogs to Thompson taken. Motivations such as experimenting solely Common would, potentially, make progress for academic interest, releasing surplus captive towards a published reintroduction strategy and stock, rehabilitation for welfare purposes, improve the conservation status of a European attracting funding or public profile, or moving and national priority species. The translocation organisms to facilitate economic development are risks are low (no adverse impacts have been not regarded here as conservation purposes. identified at the first reintroduction site after ten years of monitoring species and habitat and biosecurity measures have been implemented during stock management). 2. Species or populations that have small or The northern pool frog is a distinct form (strictly declining populations or ranges, and/or high speaking, a clade) which has a small global probabilities of extinction, will often be prime range; it is confined to approximately 150 ponds candidates. The metrics used by the IUCN Red in Sweden, Norway and Finland. Unusually for a List status can be used to assess the potential conservation project in England, the pool frog need for conservation intervention. reintroduction is a significant contribution to securing the global status of a taxon. Country- level IUCN Red-listing has not been completed, but would likely indicate northern pool frogs to be at a high threat status. 3. While the ultimate aim of any conservation The receptor site (Thompson Common) is a translocation is to secure a conservation benefit, legally protected site within a nature reserve this benefit may need long-term or permanent managed by Norfolk Wildlife Trust, a project management support to persist. Such obligations partner, guaranteeing long-term support and and their cost implications should be included in management. any assessment of alternative conservation solutions (below). 4. Conservation priorities exist at the levels of The northern pool frog is a priority for species, biological communities and ecosystems conservation action (specifically translocation) for different purposes. Candidate species for because it is a globally rare, evolutionary distinct conservation translocation might be accorded form and a flagship species for the pingo habitat priority based on biological criteria such as their at Thompson Common. Its conservation ecological role, their evolutionary distinctiveness importance is highlighted by its listing on UK and or uniqueness, their role as flagship species, their European legislation, and UK biodiversity degree of endangerment, or their potential as initiatives. ecological replacements. Translocations may be promoted on grounds of cultural heritage and its restoration but this alone is not conservation benefit. The pivotal criteria for justifying any conservation translocation will be situation- and species-specific.

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5. Where species are extinct, consequent This point does not apply to the current proposed changes in the ecosystem can indicate a need to reintroduction. The species is not globally restore the ecological function provided by the extinct, and no ecological replacement is lost species; this would constitute justification for warranted. exploring an ecological replacement. Annex 3.2 Assessing extinction causes 1. Any proposed conservation translocation These two points are addressed together. should be justified by first considering past Causes of extinction have been reviewed in the causes of severe population decline or extinction. Reintroduction Strategy1. A major cause of There should be confidence that these past widespread population decline is believed to be causes would not again be threats to any habitat loss caused by land drainage, for example prospective translocated populations. the wholesale drainage of the Fens since the 2. Threats need to be identified through all 17th century and specifically the drainage of seasons and at appropriate geographic scale for Fowlmere Fen2. Specific contributory factors the species, taking account of the species’ identified at Thompson Common include: biological attributes and life history.  lowered water table (major threat3),  scrub encroachment/reduction in grazing pressure,  frequent dry summers,  collection. Habitat restoration undertaken by NWT has addressed the main extinction factors. This includes installing sluices to hold water on site, clearing scrub and secondary woodland and reinstating livestock grazing. The release site is on part of the reserve not open to the public, hence reducing the risk of collection. Weather events cannot be resolved directly but the lowered water table (and consequently the issue of dry summers) has been addressed by NWT’s water management measures. 3. During a species’ absence, potential new The species’ absence has been relatively brief threats to any restored population may have and no new threats have been identified during arisen. that time, although predation and other stochastic events may threaten a reintroduced pool frog population while it remains small during the early stages of establishment. These threats support the need for the proposed reintroduction rather than detract from it. In addition, there may be an emerging threat posed by accelerated aquatic vegetation growth facilitated by nitrogen deposition. Consideration of this and measures to address the potential threat (mechanical intervention) are provided in the current proposed reintroduction plan.

1 Buckley, J. & Foster, J. (2005). Reintroduction strategy for the pool frog Rana lessonae in England. English Nature Research Report 642. English Nature, Peterborough. 2 Wolley, J. (1847). Is the edible frog a true native of Britain? Zoologist 5, 1821-1822; Snell, C. (1994). The pool frog - a neglected native? British Wildlife 6(1), 1-4. 3 (Beebee & Wycherley, 2001)

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4. All threats, direct and indirect, that might Direct threats are addressed elsewhere in this jeopardise attainment of the stated conservation section of the appendix. An indirect threat is benefit of the translocation should be identified posed by recreational fishing at Thompson and measures specified by which these threats Water, approximately 2 km from the pool frog would be mitigated or avoided. reintroduction site. This does not directly threaten pool frogs but anglers at a limited number of other sites have introduced water frogs to fishing lakes either to provide a food source for fish or for use as bait. The potential establishment of water frogs other than northern pool frogs would threaten the genetic integrity of the current proposed reintroduction. This threat will be reduced by working with NWT to raise awareness within Thompson Water Fishing Club of the threats posed by introductions of non- native species. 5. The spatial extent of a threat should be Threats operating over a large part of the historic considered. Threats causing local extinctions are range are historic (widespread land-use change, often acute but controllable, but threats that specifically drainage). The second reintroduction operate over all or a large part of the species’ site has not been drained so this threat is absent. range (such as pathogens, introduced predators Atmospheric pollution in the form of nitrogen or competitors, widespread land-use change, deposition may be a factor in accelerated atmospheric pollutants and climate change) are vegetation growth, but this can be more difficult to manage. accommodated by appropriate habitat management. Potential threats posed by pathogens will be minimised by adherence to biosecurity protocols developed by the Institute of Zoology. At the site level, threats have been addressed by favourable habitat management and will continue to be so by grazing and mechanical intervention to maintain ponds. 6. The severity of impact or sensitivity to a threat Northern pool frogs have relatively low genetic may vary with demography or life stage. Threat diversity but this does not appear to be the cause assessments need to consider the adaptive of population extinctions4. Northern pool frogs capacity of the focal species; this capacity will still demonstrate phenotypic plasticity (in tadpole tend to be higher in populations with high genetic growth and development) as well as the capacity diversity, long-range dispersal and/or effective to adapt to local climatic conditions5. colonisation ability, short lifespans/high reproductive rates, phenotypic plasticity, and rapid evolutionary rates. 7. Threats can be biological, physical (such as Unsecured funding is a potential threat. Funding extreme climate events), or social, political or for some short-term measures has been economic, or a combination of these. obtained, but there is no long-term funding which is often the case for wildlife projects in the UK. Biological and physical threats have been considered and addressed elsewhere in this reintroduction plan.

4 Sjögren, P. (1991). Genetic variation in relation to demography of peripheral pool frog populations (Rana lessonae). Evolutionary Ecology 5, 248-271. 5 Orizaola, G. & Laurila, A. (2009). Microgeographic variation in temperature-induced plasticity in an isolated amphibian population. Evol. Ecol. 23: 979-991; Orizaola, G., Quintela, M. & Laurila, A. (2010). Climatic adaptation in an isolated and genetically impoverished amphibian population. Ecography 33, 730-737.

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8. Threats may be inferred from anecdotal Documented observations6 are that ponds used observations of conditions around the time of by pool frogs at Thompson Common became extinction, with subsequent rigorous testing of the overgrown by emergent vegetation and anecdotes. increasingly shaded by scrub and tree growth, which was coincident with pool frog extinction and believed to be a key factor in this. These observations of changes in habitat driven by a reduction in grazing are consistent with historical aerial photographs. Understanding of pool frog ecology and monitoring the first reintroduction confirms that northern pool frogs require warm (i.e. unshaded) ponds or those in early successional stages (i.e. with relatively little vegetation growth and hence shading). The first reintroduction site is managed by grazing, with positive outcomes documented. 9. It is useful to consider multiple hypotheses for Multiple hypotheses have been considered in the causes of extinction or decline and to test these context of available evidence (land-use changes, based on the available evidence; where especially drainage and, specific to this site, significant uncertainty exists, an experimental reduced grazing and lowered water table). The approach within the translocation programme can scope of the pool frog reintroduction to date is provide guidance for implementation. insufficient to permit trials of different translocation or habitat management measures. Nevertheless the programme includes rigorous monitoring which does at least allow determination of the success of the reintroduction as a whole and, if necessary, adaptive management. 10. A trial release may answer uncertainties such A further trial release is unnecessary because the as the identity of past threats, but should only first reintroduction addresses these issues. For be contemplated where all formal requirements the purposes of compliance with the IUCN have been met, where consequences will be reintroduction guidelines, the first reintroduction suitably monitored and will be used to refine may be considered a trial release. further release design, and any unacceptable impacts can be mitigated or reversed. Annex 3.3 Considering alternatives Many conservation translocations will yield conservation benefit only at high cost and with considerable risks. Therefore, irrespective of any conservation priority assigned to the species, any proposed translocation should be justified through comparison with alternative solutions, which might include: 1. Increasing habitat availability through Negotiations are in progress to extend the size of restoration, connectivity, corridor establishment, the first reintroduction site. But even if this is or habitat protection (area-based solutions), achieved, there is no scope for colonisation of further sites by corridors because the specific habitat requirements of pool frogs, limited dispersal abilities and unmovable barriers to dispersal.

6 Buckley, J. (1974). Thompson Common with notes on the distribution of the edible frog Rana esculenta in Norfolk. Unpublished report to the Nature Conservancy Council; Snell, C.A. (2006). Genetic and ecological investigations of European populations of the pool frog, Rana lessonae (Camerano, 1982), with allied, osteological and species identification methods. Unpubl. Thesis, University of Greenwich.

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2. Improving the viability of extant populations There is only a single population of northern pool through management interventions such as frogs extant in England. This occupies a site that pathogen, predator or invasive alien species is already carefully managed. There may be control, food provision, assisted reproduction, or some scope to increase viability through predator protective fencing (species-based solutions), control, although the effect and desirability of this are uncertain and legal restrictions are a constraint. Other than this, there is no scope to increase viability of the extant population through other management intervention. 3. A variety of tools including establishment of Changes in legislation have already occurred (the protected areas, changes in legislation or pool frog is included in schedule 2 the Habitats regulations, public education, community-based Regulations). The proposed second conservation, financial incentives or reintroduction includes public education within a compensation to promote the viability of the wild communications strategy, but this is a populations can be valuable either on their own supplement rather than an alternative to the or in combination with area- or species-based reintroduction. Financial incentives and solutions (social/indirect solutions), compensation are not relevant to the pool frog reintroduction. 4. Doing nothing: inaction on behalf of a rare and Doing nothing carries a higher risk than declining species may carry lower risks of proceeding with a second reintroduction. The extinction compared to those of alternative current status (a single population) carries an solutions, and the focal species might adapt inherent risk of extinction due to stochastic naturally where it is or adjust its range without events, natural population fluctuations and human intervention (no action). human intervention (e.g. collection). 5. A conservation translocation may be used as The currently proposed reintroduction is the one solution amongst these other approaches. major solution amongst other approaches (increasing habitat availability and public education).

Annex 4 Planning a translocation 1. The goals, objectives and actions should take These two points are addressed together. into account the commonly observed phases of Studies show that amphibian reintroductions may development of successfully translocated take a long time to become established. populations: Monitoring is, therefore, undertaken as a long-  The Establishment phase starts with the first term commitment. The first reintroduction has release and ends when post-release effects been monitored since its inception in 2005. Even are no longer operating; these effects can now, this population does not appear to have include the effects of the translocation completed the Growth phase as defined here. process, chance events in small populations, Monitoring planned for the second reintroduction or a delay before reproduction occurs, all of will, similarly, be long-term in nature. which may slow initial growth.  The Growth phase is often characterised by high rates of increase and/or expansion of range, continuing until the population approaches carrying capacity.  The Regulation phase starts with the reduction in survival and/or recruitment due to increased population density. 2. The rates and duration of the Establishment and Growth phases will vary widely and be species-specific.

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Annex 5 Feasibility and design Annex 5.1 Background biological and ecological knowledge. 1. Information on the biology and ecology of wild Literature has been thoroughly researched for the populations (if they exist) should be collected or first reintroduction and understanding has been collated from available publications, reports, added to by systematic monitoring. The Pool species action plans and consultations with Frog Expert Group includes professional and relevant species experts including both amateur naturalists, which facilitates ongoing professional and amateur naturalists. consultation. 2. Background biological knowledge should The extent of knowledge of these aspects is cover aspects such as: reproduction, mating variable but key sources of information have systems, social structure and behaviour, physical been identified, including: adaptations, individual growth and development,  Buckley (1986)7 parental care, population dynamics in indigenous  Sjögren (1988)8 range.  Sjögren Gulve (1994)9 In addition, considerable knowledge has been gathered through experience with the first reintroduction. 3. Background ecological knowledge should Knowledge of these aspects is variable but key include biotic and abiotic habitat requirements, sources of information have been identified and intraspecific variation, adaptations to local summarised in the Reintroduction Strategy10. The ecological conditions, seasonality and phenology, project managers have also considered more dispersal, and interspecific relationships including recent advances in knowledge. feeding, predation, disease, commensalism, symbioses and mutualisms. 5.2 Models, precedents for same/similar species 1. Some type of modelling should be used to These four points are addressed together. predict the outcome of a translocation under Modelling to predict the outcome of translocation various scenarios, as a valuable insight for (specifically) has not been undertaken. selecting the optimal strategy. Nevertheless, population viability analysis11 has 2. It is always useful to construct a basic been carried out and has informed the first conceptual model (for example, verbal or reintroduction. The first reintroduction has diagrammatic), and then to convert this to a provided an understanding of growth and quantitative model if possible. development rates and reproductive output 3. Modelling and planning should be informed by following translocation. data from previous species management activities including translocations of the same or similar species. 4. If data are not available for the species, inferences can be made from closely related sub- species and/or ecologically similar species.

7 Buckley J. (1986). Water frogs in Norfolk. Trans. Norfolk Norwich Nat. Soc. 27, 199-211. 8 Sjögren, P. (1988). Metapopulation biology of Rana lessonae Camerano on the northern periphery of its range. PhD thesis, Uppsala University. 9 Sjögren Gulve, P. (1994) Distribution and extinction patterns within a northern metapopulation of the pool frog, Rana lessonae. Ecology 75(5): 1357-1367. 10 Buckley, J. & Foster, J. (2005). Reintroduction strategy for the pool frog Rana lessonae in England. English Nature Research Report 642. English Nature, Peterborough. 11 Williams, C. & Griffiths, R.A. (2004). A population viability analysis for the reintroduction of the pool frog (Rana lessonae) in Britain. English Nature Research Report 585. English Nature, Peterborough.

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5.3 Habitat 1. As habitats vary over space and time, species’ Climatic changes appear to be allowing ranges are dynamic. Environmental conditions thermophilic species, including water frogs, to will continue to change after species extinction. It become established outside their historic is invalid to assume that former range will ranges12. Nevertheless, after consideration of all invariably provide suitable habitat. habitat requirements Thompson Common still appears to provide suitable habitat (subject to habitat management). 2. It is insufficient to address only the causes of Excessive aquatic vegetation growth (possibly the original population decline as other threats due to increased levels of diffuse pollution) may may have emerged during any period of be an emerging threat. Mechanical pond extinction. intervention measures may be required to address this and these are included within the currently proposed reintroduction plan. No other new threats appear to apply. 3. It is essential to evaluate the current suitability These two points are addressed together. of habitat in any proposed destination area. Assessment has considered both aquatic and 4. Although the habitat requirements of large, terrestrial habitats required for the complex life generalist animal species may be easy to infer, cycle of this species13. this will not usually be the case with many taxa, for instance those with complex life cycles such as migratory species or invertebrates with larval stages. 5. A habitat assessment should include These two points are addressed together. There assurance of essential seasonal or episodic is a reasonable degree of assurance as pool environmental variation. frogs were present at the second reintroduction 6. The occurrence and severity of episodic or site until relatively recently (the 1990s), unpredictable events that are extreme and presumably experiencing similar seasonal and adverse for the species should be assessed. episodic environmental variation. 7. The release area should be large enough to The population target from the Reintroduction support the stated population targets. The Strategy is presence as viable populations on a effective habitat area will depend on the size and series of representative sites. The currently isolation of individual patches if the habitat is proposed reintroduction area includes 14 ponds fragmented. and it is set within a 140-ha nature reserve which should offer further suitable habitat. The reintroduction area should be sufficient to support a viable population and natural expansion of this may allow a larger metapopulation to become established. 8. Given the prevalence of habitat fragmentation, The pool frog is a ‘textbook’ metapopulation conservation translocation designs may include species14. The Reintroduction Strategy identifies increasing connectivity between habitat networks of breeding sites as a key habitat fragments to establish a metapopulation (a set of requirement. populations with some dispersal between them). 9. For some taxa, habitat quality and proximity to Not relevant in this case (habitat quality and other sites may be more important determinants patch size are both favourable at Thompson of habitat suitability than habitat patch size. Common).

12 Wycherley, J. (2003). Water frogs in Britain. British Wildlife 14(4), 260-269. 13 Baker, J. (2012). Review of secondary reintroduction sites for the pool frog. Unpublished, confidential report for Amphibian and Reptile Conservation. 14 Sjögren-Gulve, P. & Ray, C. (1996). Using logistic regression to model metapopulation dynamics: large-scale forestry extirpates the pool frog. In: McCullough, D.R. (ed.) Metapopulations and Wildlife Conservation. Island Press. Washington, DC

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10. Achieving suitable habitat may require its Considerable habitat restoration has been restoration or even creation, or removal of alien undertaken by Norfolk Wildlife Trust at Thompson or nonindigenous animals or plants that were a Common (extensive removal of trees and threat in the past to the focal species or would be reintroduction of grazing management). a threat again for translocated individuals; any such removal should be done as humanely as Non-native amphibians are not known locally possible and in a manner that causes minimum (although the potential for future introduction is disruption to habitats or other species. addressed within the current Reintroduction Plan). Crassula helmsii has been found on Thompson Common. Ponds where it occurs will not be disturbed by mechanical intervention to minimise risk of spread, and site staff are vigilant towards introduction so that remedial action can be taken rapidly. 11. While no organisms should be released The effort expended on habitat assessment is without assessment of habitat quality in the proportional. Habitat within the reintroduction destination area, the level of effort expended on area has been assessed, as has habitat within assessment should be proportional to: the scale the surrounding nature reserve. The level of risk of area likely to be affected by the translocation from the proposed reintroduction is minimal, and subsequent establishment, the degree of especially given that the species used to occur on certainty on the expected performance of the site until recently. released organisms, the level of risk of undesired and/or harmful outcomes, the ability to reverse unacceptable outcomes. 12. Assessing habitat requirements will involve Members of the Pool Frog Expert Group have surveys of extant populations of the focal species visited pool frog sites in Sweden (the core range) if they remain in the wild. However, current range to assess habitat. The first reintroduction site in can be an unreliable indicator of habitat England has been monitored since 2005. requirements if remnant populations have been Information gleaned from both of these sources forced into refuges of sub-optimal habitat. has been used to inform the understanding of habitat requirements. 13. The possible ecological roles of the focal Pool frogs are highly unlikely to have a significant species in any new environment should be negative impact on other species or habitats. carefully evaluated, with the particular concern They will constitute potential prey items for some that the conservation interests of other species invertebrates, birds, mammals and reptiles. They and habitats will not be jeopardised by the will be predators of some invertebrates. They will translocation (Section 6). be host to parasites. However, none of these roles is expected to substantially disrupt local trophic dynamics or population sizes. 14. Plants, fungi and invertebrates that are The specific habitat requirements of northern pool immobile for at least part of their life cycle, frogs mean that it is relatively straightforward to require microsite assessment potentially at the define areas likely to be colonised. In this case scale of centimetres; in contrast, large animal pool frogs are unlikely to spread far beyond species living in extreme or unpredictable Thompson Common enabling an assessment of conditions will require areas that will vary likely habitat. unpredictably in size and location 15. As even the most detailed habitat The currently planned second translocation will assessments may not capture the full range of take place over three to four years, which will go environmental variation during the lifespan of some way to addressing losses of individual individuals of the focal species, the loss through frogs. death or dispersal of translocated individuals at some sites or in particular years should be expected.

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16. A candidate species may be linked with other There are no known essential co-dependents of species either through a shared ecological northern pool frogs. (Pool frogs in some dependence or as providers of critical functions populations are a host species to sexual such as being a sole pollinator, a symbiont or parasitism of edible frogs but pool frogs are not host. Any destination area should be surveyed for dependent on edible frogs). the presence of any essential co-dependents of the focal species. It may then be necessary to translocate these essential species with the focal species; alternatively, species indigenous to the destination area may be able to assume these roles. 17. The release area and essential habitat for the Thompson Common is part of a SSSI and is translocated organisms should be secure from managed by Norfolk Wildlife Trust. It is also part incompatible land-use change before the of Norfolk Valley Fens SAC. Site protection and conservation goal is reached, and, ideally, in management give it a high degree of security perpetuity. from incompatible land-use change. 5.4 Climate requirements 1. The climate requirements of the focal species The northern pool frog occurs in isolated should be understood and matched to current populations at the edge of the species range. It and/or future climate at the destination site. is thermophilic species so warm sites and microhabitat are key to its survival here. The historic range in England included the destination site and frogs were present here until relatively recently so climate is broadly similar to when the species was extant here. Climate change may allow water frogs to increase their northern range15 so as far as ecological predictions can be based on an increasingly extreme climate, conditions at the destination site should be favourable. 2. The climate requirements of any candidate These two points are addressed together. The species for a conservation translocation can be northern pool frog has a small global range and assessed through measurement of key climate so would be prone to underestimation of the parameters in the species’ current range; this breadth of potentially suitable habitat. Moreover, should include the extent of climate variation given that the proposed reintroduction is within tolerated by the species based on its distribution; the recent historic range then bio-climate the resulting bio-climate envelope can be used in modelling seems is a disproportionate measure. models of predicted climate change to assess how the focal species might respond to scenarios of future climate; the results can be used to identify potentially suitable destination locations. However, the utility of this approach depends on many factors such as the availability and quality of data, spatial resolution and the climate change scenarios used; in addition, the bio-climate model for a species with a small, remaining range will under-estimate the breadth of potentially suitable climatic conditions. 3. A climate envelope model should be supplemented by a study of other factors that might determine habitat suitability and distribution, such as the presence of essential or co-dependent species, the effects of predators, competitors, disease etc.

15 Wycherley, J. (2003). Water frogs in Britain. British Wildlife 14(4), 260-269.

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4. Any determination that an area is habitat for a As above, climate change may benefit the conservation translocation should include northern pool frog. Although there are reassurance that its climate is predicted to remain uncertainties regarding the length of time suitable for the reintroduced species for long required to establish a pool frog population it enough to achieve the desired conservation seems unlikely that climate change will occur to benefit, acknowledging the uncertainties inherent the extent that this is unattainable. in climate projections. 5.5 Founders Genetic considerations 1. Any source population should be able to The proposed reintroduction will use individuals sustain removal of individuals/propagules, and head-started from the egg stage, which will removal should not jeopardise any critical minimise the impact of removal of animals from ecological function, except in the case of an the source population. emergency or rescue removal. 2. If there is little genetic variation in source These two points are considered together. material used for translocations, there are two Limited genetic variation appears to be the potential risks: the first is that reproduction natural situation for the northern pool frog16 between related individuals can lead to reduced although it has demonstrated phenotypic vigour, reproductive output and survival plasticity in spite of this17. Founders will be (inbreeding depression); the second is a lack of sourced from multiple egg clutches over three to adequate genetic variation to enable survival and four years, meaning that there will be genetic adaptation in the face of environmental change. variation in the founders, to the extent that is 3. Such genetic problems can occur due to possible with a single source population. Future sampling a source population with low genetic research is anticipated to address whether the diversity (typically small/isolated populations), population might be genetically constrained. biased sampling of a single source population, genetic bottlenecks in the translocation process, and unequal survival, establishment and reproductive output in the destination area. 4. If founders originate from environments There are differences between environments in markedly different to the destination area, there is Sweden and the reintroduction sites in England a risk of failure due to their being poorly adapted but the key habitat elements were identified in the to the destination area. original Reintroduction Strategy and the initial reintroduction site managed accordingly, reducing the risk of that frogs were poorly adapted to their new environment. The same applies to the proposed destination area, which is very similar to the first reintroduction site. The proposed reintroduction may also benefit from adaptation to local environmental conditions that may have occurred already at the initial reintroduction site. 5. If a translocation programme involves mixing Populations will not be mixed in the proposed populations, there is the potential for fitness costs reintroduction. associated with genetic incompatibilities between different lineages (genetic outbreeding depression). Predicting the situations in which genetic incompatibilities may occur is not simple, and the fact that problems may not become apparent for 2-3 generations makes pilot testing difficult. However, recent metaanalyses provide useful working principles.

16 Sjögren, P. (1991). Genetic variation in relation to demography of peripheral pool frog populations (Rana lessonae). Evolutionary Ecology 5, 248-271; Zeisset, I. & Beebee, T.J.C. (2001). Determination of biogeographical range: an application of molecular phylogeography to the European pool frog Rana lessonae. Proc. R. Soc. B 268: 933-938. 17 Orizaola, G. & Laurila, A. (2009). Microgeographic variation in temperature-induced plasticity in an isolated amphibian population. Evol. Ecol. 23: 979-991.

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6. Taking individuals from multiple populations There is only a single potential donor population can increase the genetic diversity and decrease so this is not an option. the risk of inbreeding depression in the translocated population. This is appropriate if outbreeding depression and/or (for animals) behavioural differences between the populations are considered unlikely. 7. More radical strategies involve greater This point does not apply to the current proposed geographical or ecological distances between reintroduction. source and destination sites, and/or greater mixture of source material from multiple populations. 8. Multiple sourcing aims to provide a balance These four points are considered together. There between using primarily local/ecologically similar is only a single potential source population so source material, and introducing decreasing sourcing translocation stock from multiple sites is proportions of genotypes with increasing not currently and option. Anticipated future geographical/ecological distance from any research may address whether a further population at the destination site. This is introduction from Sweden, for genetic rather than designed to mimic the beneficial influx of ‘useful’ demographic reasons, might be warranted. genetic variants from occasional long distance gene flow, without swamping out locally adapted variants. This approach is recommended for fragmented habitats in which either the fragments contain inbred individuals or their populations are considered unlikely to possess adequate genetic variation to respond to environmental change. 9. Predictive sourcing aims to introduce genetic diversity that will be adapted to the predicted direction of environmental change. The challenge is to introduce material adapted to future environmental conditions, without being so maladapted to current conditions that it suffers immediate fitness consequences. 10. A combination of multiple and predictive sourcing is a logical, but largely untested strategy for translocations in fragmented systems which are likely to suffer detrimental effects of climate change; it may be especially considered for conservation introductions. 11. The relative risks and benefits associated with the choice of source population(s) will vary depending on the goals and type of translocation and source population availability. A species’ life history traits are also relevant as they are major determinants of the amount and spatial distribution of a species’ genetic variation. As the ‘mixture approaches’ to translocations essentially involve providing variable source populations upon which natural selection can act, such sourcing may result in increased mortality, with possible consideration for animal welfare. 5.6 Disease and parasite considerations 1. Surveillance of source populations can The source population has been rigorously establish the potential pathogen community assessed by a leading authority, and so present; individuals can then be selected for significant pathogens have been identified. purposes of reintroduction or translocation, based on a risk assessment.

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2. All aspects of the translocation process can The proposed translocation will entail head- cause stress-induced disease: the conditions and starting tadpoles and releasing peri-metamorphic duration of any quarantine, inappropriate disease froglets. The impact of stress-related disease prevention protocols, poorly designed transport during this process is unknown. Sound containers and methods of transport, extended husbandry is probably the best measure to time in transport, and lack of adaptation prior to minimise stress of eggs and tadpoles. A protocol transport can contribute to the occurrence of for this has been developed18. disease and mortality during the translocation process. 3. The possibility of infection through interaction Biosecurity protocols have been developed with human, domestic animal or inanimate specifically for the pool frog reintroduction elements during the translocation process is programme. These have been reviewed and always present and in practice unpredictable; amended, most recently in 201419. effective biosecurity is, therefore, a requirement throughout. 4. Tools for management after release, such as This point does not apply to the currently feeding stations that concentrate or mix released proposed reintroduction. and wild conspecifics, may promote the exchange of pathogens. 5. Pathogen risk assessment of translocated This point does not apply to the currently plants should include the possibility of infection proposed reintroduction. through interaction with wild and domestic plants, disease vectors or inanimate components during the translocation process. 6. If an extinct host had parasites that also There is no information regarding extinct became extinct, then it is desirable from a parasites so this point cannot be addressed. restoration perspective to re-establish those parasites with the translocated host; but, this should be subject to especially rigorous assessment of the risks to the same or other species in the destination area; an apparently benign mutual relationship between host and parasite at source may change adversely for the host in the destination environment. 7. Translocations within geographical/ The current translocation involves closely spaced administrative areas sharing diseases may not source and destination sites so extensive disease need extensive disease screening, but attention screening may not be needed. Nevertheless, a to managing infection threat should increase with disease risk assessment is in preparation the distance between source and destination (Shotton & Sainsbury, 2015) and all aspects of sites. the translocation will be subject to biosecurity measures.

18 Baker, J. (2014). Pool frog head-starting 2013. Unpublished, confidential report to the Pool Frog Reintroduction Steering Group. 19 Peniche, G. & Sainsbury, T. (2014). Pool frog (Pelophylax lessonae) reintroduction project: Disease risk management & post-release health surveillance protocol 2014/2015. Unpublished report, Institute of Zoology, Zoological Society of London.

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Annex 6 Risk assessment 6.1 Assessing the risk landscape

6.2 Risks to the source population 1. Where a translocation involves removal of Removal of individuals from the source individuals or propagules from existing wild population will reduce the numbers present there. populations, any potential negative impacts on The proposed use of head-starting will minimise the source population should be assessed. this impact (removal of an egg is less likely to impact the donor population than removal of a breeding adult). 2. If removal of individuals or propagules from a Removing eggs will cause a (small) reduction in source population causes a reduction in its short-term viability of the source population, but viability in the short term, the translocation this is outweighed by the potential gain in species objectives should include balancing this with the viability (two populations/sites instead of one). expected gain in viability of the destination This gain should be achievable within five to ten population, so that the species has a greater years. overall viability than without the translocation, within a stated time period. 3. Translocations can affect not only the source No risks to associated/dependent species in the populations of the focal species but may also source site have been identified, and it is unlikely have negative effects on associated/dependent that any dependent species occur. species in the communities from which those individuals are removed. 4. It may be beneficial to use non-viable This point does not apply to the currently populations as sources of stock. proposed reintroduction.

6.3 The ecological consequences of translocation Ecological consequences, points 1-5. These points are generic points considered in other sections of the IUCN Guidelines and the current plan.

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6.4 Disease risk 1. As it is not possible, despite all appropriate Three bacterial species of potential concern have precautions, to ensure that translocated been identified from pool frogs during post- individuals of any species are completely free of release monitoring, summarised in the all disease/pathogen risk, risk assessment should Discussion section of Vaughan, et al. (2010)20. It therefore focus on known pathogens in the is, however, not straightforward to categorically translocation stock that are likely to have determine their origin or pathogenic status, but undesirable impacts on other organisms at the overall they are not considered to be of concern destination. Generalist pathogens with no known for the reintroduction. history at the destination are a particularly high risk. None of the bacteria have been reported previously in free-living amphibians elsewhere in the United Kingdom. However, this should be regarded in the context that knowledge of bacterial/native amphibian relationships is very limited. The bacteria are, on the other hand, common in wet environments, and so their presence in wild amphibians is unsurprising.

Importantly, populations of resident amphibians and pool frogs at the first reintroduction site have shown no signs of significant population decrease, and in fact several species show substantial increases. 6.5 Association invasion risk Where inadequate biosecurity protocols have The pool frog reintroduction programme has been resulted in further species being introduced with subject to specifically designed biosecurity the translocated organisms, there is a risk of the measures at all stages and will continue to be so. former becoming invasive in the release area. If Implementation of these measures enabled this happens, the benefits of the translocation detection of the fish louse, Argulus foliaceus on may be insignificant compared to the damage tadpoles of donor stock prompting manual done by the invasive species. removal21. This species is already relatively common in the wild in Norfolk so it is not considered a serious risk. Moreover, screening measures in place prevented its introduction along with the pool frogs; no lice have been detected in monitoring.

The current proposed reintroduction will use head-starting, which entails taking eggs rather than other stages. This greatly reduces any risk of translocation of associated species.

20 Vaughan, R., Peniche, G., Molenaar, F. & Sainsbury, T. (2010). Disease risk management and post-release health surveillance of the pool frog (Rana lessonae) reintroduction programme 2010. Unpublished report. Institute of Zoology, Zoological Society of London.

21 Foster, J. (2005). Report on the first release in the reintroduction of the pool frog Rana lessonae to England, August 2005. Unpublished report.

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6.6 Gene escape Intraspecific hybridisation The only existing population is the translocation 1. Where translocations involve reinforcement, or source so there is no risk of its reduction in reintroductions close to existing populations, vigour. Moreover, unassisted migration of frogs there is a risk of genetic swamping of the resident between the two sites is impossible within a population(s) by the translocated individuals. This reasonable timescale. can potentially cause a reduction in vigour or reproductive success in a small, stable, resident population if a large proportion of the subsequent reproductive output is derived from the less well- adapted translocated stock. Interspecific hybridisation There are no populations of closely-related 1. Translocation of a population into the close species nearby. vicinity of a closely related species may result in inter-specific hybridisation which would not have occurred naturally. This is particularly likely in cases where a conservation introduction moves a species out of its extant range and overcomes natural geographical barriers to hybridisation with related species. In these situations, hybridisation can potentially threaten the genetic integrity/distinctiveness of the resident species, and in extreme cases extinction-by-hybridisation is possible. 6.7 Socio-economic risks 1. The risk assessment should cover the potential  No direct negative impacts on human interests direct and indirect negative impacts on human have been identified. interests:  No threats to food supplies or ecosystem • Direct effects on people and livelihoods such as services have been identified. potential or perceived dangers from released plants, animals and fungi, and the adverse public relations arising from any incidents, • Indirect ecological effects that could threaten food supplies or ecosystem services such as clean water, erosion control, pollination, or nutrient cycling 6.8 Financial risks 1. Where a translocated species causes The northern pool frog is at the north-western significant, unacceptable consequences, such as edge of its species range. As such it has specific its increase to damaging, pest status, the likely habitat requirements which make it highly unlikely outcomes are: to become a pest species. In any case, it is  remedial costs may be very high, difficult to imagine how pest status would be  remedial costs cannot be met from project manifested by this species, since it is not known funds, to have impacts on socio-economic interests  funding for future conservation translocations anywhere in its range. is less likely.

Annex 7 Release and implementation This section covers the specific and proximate factors that will shape founder demographics for maximum chance of successful release and establishment, and the variety of possible supportive management actions.

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1. The most appropriate life stage for The head-starting protocol will take eggs and translocation should be identified. result in the release of peri-metamorphic froglets. This protocol takes advantage of the reproductive potential of amphibians22 and minimises any impact of removal from the source population. 2. The optimum number of individuals to This point has been considered and, although translocate will vary from species to species and there is an unavoidable element of trial-and-error with the objectives of each translocation. The (due to e.g. uncertainties over finding spawn optimum number will be a trade-off between clumps, and variation in clump size), impact on the source population and reducing the approximately 12 clumps of spawn should risk of the founder population failing to establish produce sufficient metamorphs (600-1000) because of random effects on a small population, annually. Numerically this is the equivalent to the and lack of genetic diversity. reproductive output of 2-3 females, which would be effectively lost from the source population. 3. Mortality in the translocated population may A population viability analysis carried out mean that the number of effective founders is specifically for the pool frog reintroduction23 considerably less than the number translocated. concludes that 980 metamorphosing tadpoles should produce 200 one-year olds. 4. While successful establishment of translocated The selection of metamorphs was made to populations often depends on the release of balance costs/benefits summarised in 7.1 above individuals in natural sex ratios and age classes but this may also have benefits under this point (and social groupings in animals), it may be because it mimics natural colonisation of new enhanced by deliberate bias in founder selection, sites (juveniles tend to be the dispersal phase in for example either by increasing the proportion of amphibians, adults are more sedentary). individuals of breeding age or by favouring the proportion of juveniles; any such strategy will be specific to the species and circumstances. 5. Plant founder selection will be influenced by This point does not apply to the current proposed the age class most amenable to successful reintroduction. transplanting. Etc. 6. Population models can assist in determining Post-release monitoring information suggests that the optimal strategy in terms of trade-offs head-started individuals made a significant between source and founding populations, and in contribution to the number of frogs found at the the optimal selection of numbers and composition first release site24. The success of this head- of founders. After initial release, information from starting indicates that releases of approximately ongoing monitoring can define the optimum 1,000 metamorphs are required each year over a number and size of further releases through three or four year period. adaptive management. 7. Where individuals are sourced from small and This applies to the currently proposed declining populations, their number, age and sex reintroduction which has opted to take eggs composition may be determined only by what is rather than any other life stage. available. 8. The life history, ecology and behaviour of the In pool frogs (and other amphibians) the juvenile focal species, together with any seasonality in stage tends to be the stage during which essential resource availability, should guide dispersal and colonisation of new breeding ponds scheduling of releases; species may have occurs. The release of metamorphs mimics the periods of development during which they are natural colonisation process. more predisposed to disperse, establish home ranges, have higher mortality, or breed.

22 Bloxam, Q.M.C., & Tonge, S.J. (1995). Amphibians—suitable candidates for breeding-release programmes. Biodiversity and Conservation 4, 636-644; Griffiths,R.A. & Pavajeau, L. (2008). Captive breeding, reintroduction, and the conservation of amphibians. Conservation Biology 22(4), 852–861. 23 Williams, C. & Griffiths, R.A. (2004). A population viability analysis for the reintroduction of the pool frog (Rana lessonae) in Britain. English Nature Research Report 585. English Nature, Peterborough. 24 Baker, J. (2014). Pool frog head-starting 2013. Unpublished, confidential report to the Pool Frog Reintroduction Steering Group.

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9. Releasing individuals over several years may Practice established by Amphibian and Reptile help to overcome interannual variation in climate Conservation for rare herpetofauna and and the occurrence of natural disturbances that population viability analysis25 confirm this; a three occur infrequently but with severe results. to four-year release is planned. 10. Releases at multiple sites will increase the The limited size of the source population chance of selecting favourable habitat, avoiding precludes the option of release at multiple sites. localised disturbance events, and may encourage Nevertheless, the project will release development of local sub-populations. metamorphs at several ponds within the second reintroduction site. 11. Repeat releases at one site may allow newly This point does not apply to the current proposed released animals to learn survival skills from reintroduction. Amphibian behaviour is relatively those released earlier, but the social or territorial ‘hard-wired’26 and social learning apparently does behaviour of some species may discourage such not occur. repeat releases. 12. Low survival in released organisms can be The current proposed reintroduction is an due to a wide range of health, behavioural, or initiative to diversify the overall reintroduction other ecological factors; diverse management project. Reintroduction site management options options can contribute to higher post-release are not, in themselves, diverse, but grazing is an success. option being used to increases microhabitat diversity. The project managers will be vigilant toward additional management options as the reintroduction proceeds. 13. Released animals should exhibit behaviours This point does not apply to the current proposed essential for survival and reproduction, and for reintroduction. Amphibian behaviour is relatively compatibility with any conspecifics in the release ‘hard-wired’ and limited in complexity. Social area; it may sometimes be desirable to move interactions are minimal, apparently confined to groups of animals with their social relationships breeding. intact. 14. Animals can be behaviourally conditioned The head-starting protocol takes individuals from before release to avoid predators, or to develop a wild population and maintains them in captivity predatory skills that may have been lost either for less than one generation time, so there is no over short periods or successive generations in potential for loss of genetically inherited captivity; this may be particularly valuable for behavioural traits. socially complex species; where possible, practitioners should design experiments to determine the efficacy of conditioning techniques and/or to determine correlates between prerelease behaviour and post-release survival. 15. Pre-release treatment or medication can help Treatment of disease in amphibians is poorly- to protect animals and plants from pathogens developed. The pool frog reintroduction encountered after release. programme has generally opted for reliance on biosecurity protocols to manage disease risks. However, should any disease be manifest in frogs after release then expert advice will be sought, and expertise developed by the Institute of Zoology in the first release would be useful in this context.

25 Williams, C. & Griffiths, R.A. (2004). A population viability analysis for the reintroduction of the pool frog (Rana lessonae) in Britain. English Nature Research Report 585. English Nature, Peterborough. 26 Bloxam, Q.M.C., & Tonge, S.J. (1995). Amphibians—suitable candidates for breeding-release programmes. Biodiversity and Conservation 4, 636-644; Griffiths,R.A. & Pavajeau, L. (2008). Captive breeding, reintroduction, and the conservation of amphibians. Conservation Biology 22(4), 852–861.

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16. Animals may be held for some period at the This option is not planned for the currently release site to allow them to accustom to local proposed reintroduction. The first reintroduction conditions or enhance social group cohesion; was established after a “soft” release, which was such procedures are most likely to be useful with implemented at that stage because of the greater captive-bred animals, but should never be distance involved in that translocation assumed to be useful without evidence. (international rather than local). 17. Rapid dispersal of animals from release sites Monitoring the first reintroduction has found that is common, and may be linked to stress before or pool frogs are relatively sedentary. Habitat during the release process; such movements are quality appears to be key to the degree of also often associated with immediate post- movement (pool frogs tend to remain in preferred release mortality and occasionally low habitat patches). reproductive rates; in contrast, a period of confinement at the release site can discourage translocated animals from returning to their source area. 18. Horticultural management can prepare plants This point does not apply to the currently for local conditions through modifying conditions proposed reintroduction. such as irrigation, light levels and available nutrients. 19. During or following release, the provision of No such provisions are considered necessary. artificial caging, shelters or residences, or supplementary food and water can increase survival of plants and animals, but may also promote disease transmission through artificially concentrating individuals. 20. For some species such as invertebrates, Head-starting has been selected in this case to amphibians or reptiles, ‘head-starting’ avoids the avoid the high mortality typical in the wild and use heavy mortality of young age classes in the wild; the additional ‘survivors’ as stock for the currently wild hatchlings are reared in protective proposed second reintroduction. enclosures before release at less susceptible size/age. 21. In various species, ‘fostering’ integrates This point does not apply to amphibian captive-bred or orphaned eggs/wild young with translocations and so no such action is planned. offspring that are already being raised by wildborn parents; this may allow the translocated young to be fed by wild conspecifics and to learn behaviours and traditions that may be critical for survival.

Annex 8 Outcome assessment and continuing management 8.1 Survey / monitoring before release It is desirable to collect baseline information on Baseline data on other amphibians and habitat any area before releases into it. Without it, it is has been collected prior to the release of pool difficult to ascribe observed changes after release frogs, and more data collection is planned for to the impacts of the released organisms. spring 2015. The methods used will allow comparison with post-release monitoring. The resources for pre-release survey are likely to be less than for post- release monitoring; hence, pre-release effort should focus on the species and ecological functions most likely to be affected by the translocation.

While the emphases of pre- and postrelease monitoring may differ slightly, their methods and resulting data should allow direct comparison.

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8.2 Monitoring after release While post-release monitoring is an essential part of a responsible conservation translocation, the intensity and duration of monitoring should be proportional to the scale of the translocation (in terms, for example, of the numbers of organisms released, their ecological roles, the size of area affected) and the levels of uncertainty and of risk around the translocation results. Demographic monitoring 1. Translocation objectives are often stated in Population viability analysis for the pool frog terms of desired population sizes or probabilities includes variable numbers of individuals and of extinction within defined time frames breeding ponds and distances between ponds. (Guidelines Section 4). Assessing whether Post-release modelling will collect information on populations are likely to meet these objectives these variables. Analysis of data from the first requires demographic models of populations, so reintroduction indicates that post-release the information from monitoring should be monitoring for the currently planned designed to allow choice between alternative reintroduction will allow estimates of population models and model parameters. Monitoring can size and annual survival of adult frogs. just involve estimating (or indexing) abundance, but predictions will be much more precise if data are collected on vital rates, such as survival, reproduction and dispersal. 2. Methods of estimating abundance include Peak count and capture-mark-recapture methods sample plots, with methods to account for tested during the first reintroduction have proved incomplete detectability; indices of relative satisfactory and will be repeated for the currently abundance or presence/absence surveys may be planned reintroduction. adequate, but only if objectives focus solely on the growth or spread of populations. 3. Estimating survival rates involves monitoring a Capture-mark-recapture methods used in the first sample of marked (or otherwise identifiable) reintroduction used individual photo identification individuals; incomplete detectability should to help calculate survival estimates. be accounted for to avoid biased survival estimates, and it may also be important to avoid confounding death and dispersal; where it is difficult to mark or directly observe individuals, photo identification using natural markings, or genetic monitoring, (see below) may be appropriate. 4. Estimating reproductive success involves Estimating reproductive success of individual quantifying numbers of offspring or propagules pool frogs is impractical since it would involve produced, along with establishment rates of substantial resources and would entail excessive offspring in the translocated population; this disturbance. In the first reintroduction, counts of requires field surveys to identify reproductive metamorphs were used as an index of annual individuals, their breeding locations, and the fate breeding success and this will form an element of of their offspring, especially their survival to post-release monitoring in the current planned reproductive age; alternatively, it may be reintroduction. adequate to estimate recruitment, for example through the number of new individuals entering the population per individual currently present. 5. Monitoring detail will be determined by the Pool frogs typically become sexually mature at species’ longevity and specific attributes such as two years. Most adults breed for one or two age of first reproduction. years, and a minority of individuals breed for as many as five years. Hence, post-release monitoring is undertaken as a long-term requirement. 6. Monitoring should cover the entire area Post-release monitoring will aim to determine the occupied by the translocated population. entire area occupied.

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Behavioural monitoring Behaviours which can yield insights into the Breeding behaviour will be used to gauge the adjustment of translocated animals to the adjustment of translocated animals. Observation destination area include activity and movement of calling males and amplectant pairs will be used patterns, foraging behaviour and diet selection, as indicators. social organisation, breeding season and success. Ecological monitoring 1. Ecological monitoring should be undertaken to This point does not apply to the current proposed record the ecological changes associated with reintroduction. In the case of temperate the translocation, and to contribute towards the amphibians, it is unlikely that ecological effects general knowledge basis for translocation will be evident when demographic targets are feasibility and design. It is most unlikely that any met. translocated organism can attain its intended demographic targets without evident ecological impacts. 2. Ecological monitoring is also necessary to link Post-release monitoring of both habitat and changes in habitat, for whatever reason, to the demography is planned. translocated population’s demography. 3. Unexpected consequences of a translocation Planned population and habitat monitoring and should be detected and monitored to see whether annual reviews will provide the scope to detect their longer-term impacts will be neutral, negative and monitor unexpected consequences. or positive. 4. The appearance of unintended and Planned monitoring and annual review will give undesirable adverse impacts following the scope to modify habitat management or translocation may prompt radical changes of reverse the translocation. management or even reversal of the translocation - Annex 8.3. 5. Where a translocation purpose is to restore an This point does not apply to the currently ecological function, monitoring should include a proposed reintroduction. focus on detecting and measuring the return of this function. Genetic monitoring 1. Genetic markers can establish the proportion These two points are considered together. of genetic diversity that is captured from the Referring to 8.2 of the appendices of the IUCN source populations and whether this diversity is guidelines, the intensity and duration of maintained in the transition to the established monitoring should be proportional to the scale of population at the release site(s). Tissues taken the translocation. No genetic monitoring is and stored in the early stages of a translocation programmed for the current proposed programme can be a cost-effective resource for reintroduction, although it is anticipated that future evaluation of genetic change. future research may examine this issue if an 2. In well-resourced projects, genetic monitoring opportunity arises. may also be used to make demographic inferences, such as insights into the number of adults contributing to subsequent generations, the extent to which translocated individuals in reinforcement are contributing genes to the resident population, and for gaining general insights into behavioural ecology or population size.

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Health and mortality monitoring 1. Monitoring can assess whether there are These two points are considered together. unacceptably high levels of disease/adverse Protocols for health monitoring and post mortem welfare/mortality which will impact on the success investigations for the pool frog reintroduction of the translocated population, or which may have been developed, reviewed and updated by present a threat to any neighbouring populations; the Institute of Zoology27. however, if recapture is needed for this purpose, it may only exacerbate underlying problems. 2. Identifying the causes of death accurately and precisely can be critical in assessing translocation progress and indicating the challenges facing the establishing population. Socio-economic and financial monitoring 1. The socio-economic and financial impacts of These two points are considered together. There any translocation should be monitored, especially are no anticipated negative socio-economic or in a conservation introduction. financial impacts of the current planned 2. Where such impacts are undesirable and reintroduction. Nevertheless, any such issues unacceptable, monitoring results can prompt arising will be addressed by the Pool Frog Expert changes in management or an exit strategy- Group. Annex 8.3. 8.3 Continuing management 1. Monitoring information enables managers to Habitat and species monitoring information will be assess whether objectives are being met relayed annually to the Pool Frog Expert Group according to schedule. This information can then for review, and also to Natural England. be used both to adjust any ongoing management of the current population and, more generally, to contribute to the design of other translocations. 2. Adjustments may involve increasing or Any required changes to habitat management decreasing the intensity of management or measures or intensity will be subject to an changing the type of management. For example, appropriate assessment by Natural England to if a translocated population failed to grow despite ensure compliance with the SSSI status of the ongoing management, it might make sense to reintroduction site. increase the intensity of that management. Alternatively, it might be better to try a different management option or even discontinue management and relocate the remaining individuals elsewhere. If monitoring indicated the translocated population was having undesirable impacts, this could potentially lead to a decision to control or remove the population or conduct other management actions to lessen these impacts. The decision process should be transparent, and reflect current understanding of the population’s dynamics and impacts, the values placed on different outcomes by all people involved, and the cost of management options.

27 Vaughan, R. J., Molenaar, F.M. & Sainsbury, A.W. (2011). Disease risk management of the pool frog (Rana lessonae) reintroduction project 2011/2012. Unpublished, confidential report. London, Institute of Zoology.

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3. Although decisions need to be made, it is The uncertainly of understanding populations and essential to acknowledge the uncertainty in making predictions is acknowledged. The population predictions. There are two sources of sources of uncertainty will be considered when uncertainty in these predictions. First, populations assessing project progress. are subject to random variation due to chance fates for individuals (demographic stochasticity) or to environmental fluctuations (environmental stochasticity). Second, understanding of populations is always limited, and decisions should be supported by inclusion of the assumptions behind them and the extent of uncertainty in biological knowledge of them. 4. A key benefit of monitoring is that it allows The reintroduction will be monitored to provide practitioners to progressively improve feedback to the Pool Frog Expert Group, which understanding and therefore develop more will allow adaptive management. accurate models for further predictions and objective setting. This is especially useful when The status of the pool frog in England and the original objectives cannot be met due to factors scope of the currently proposed reintroduction beyond management control. This process of does not warrant or allow active adaptive learning from management results is called management in the sense used here, but this is “adaptive management”. However, adaptive consistent with 8.2 of the appendices of the IUCN management does not mean merely adjusting guidelines, the intensity and duration of management following monitoring; it means monitoring should be proportional to the scale of having clear models in place in advance that are the translocation. then evaluated against monitoring results. It is sometimes appropriate to manipulate management actions deliberately to gain knowledge, a process known as “active adaptive management”. For example, if a translocated population is growing at the target rate under a management regime, it may make sense to temporarily discontinue the regime to ensure it is necessary. Annex 9 Dissemination of information 1. Dissemination aims to ensure that maximum The current proposed reintroduction includes a information around a conservation translocation strategy for dissemination of information to is available in timely and suitable fashion to target different target audiences (section 11). audiences. Hence, communication should start at Communications will occur at all stages of the the planning stage, followed by reporting on reintroduction. Progress will be reviewed progress at key stages of the project, and with annually with partners, all of whom are this information disseminated to all parties represented on the Pool Frog Expert Group. involved. 2. Effective communication of information through The strategy for dissemination of information the course of a conservation translocation serves meets all of these purposes (section 10 of the the following purposes: currently proposed Reintroduction Plan). • It prevents conflict with interested parties in both Bodies overseeing both source and destination source and destination areas, and generates trust areas are partners within the pool frog that any translocation is undertaken with integrity reintroduction and both are represented within and without hidden motives (the corollary is that the Pool Frog Expert Group. retrospective management of negative interactions can be costly and damaging to the translocation), • It allows the evaluation of success whilst a Post-release monitoring will allow annual translocation is in progress, and should provide a evaluation of the translocation. Translocation lasting record of methods, monitoring and results methods and the results of monitoring will be that contribute to retrospective evaluation and published to inform other translocation attempts. comparison with other translocation attempts,

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• Dissemination of results is often part of statutory Translocation via head-starting and post-release or contractual requirements, monitoring will be regulated by licences issued by Natural England. Licence return data will be required as part of the regulatory processes. • It contributes to assessments of species’ status Pond occupancy data collected during post- by providing data on survival and range, release monitoring will provide a measure of range; capture-mark-recapture data will allow survival to be estimated. • It provides a lasting record of the origins of any This information is documented in the current population Reintroduction Plan. 3. Mechanisms for communication should be The communications strategy for the currently relevant to the intended audience, but should proposed second reintroduction includes include several of the following platforms; use of elements intended for different audiences these may be combined with consultative (section 11) and includes several of the platforms processes: suggested. • Internet resources, social media, presentations Project updates will be provided on ARC’s at venues around the release area, website. • Publication mechanisms of statutory bodies The statutory body, Natural England, participates which should be publicly accessible unless good in the Pool Frog Expert Group and hence will cause is given for maintaining confidentiality. have project information to relay within NE publications. • Publication mechanisms of nongovernmental The currently proposed second reintroduction will organisations where these are made publicly be reported on in ARC’s communications available. channels, for example via website, social media and newsletters. • Databases of translocations kept by statutory The licence application will allow Natural England bodies or non-governmental organisations. to make a record of the translocation. ARC maintains a species database on which reintroduction progress will be tracked. • Meta-analyses of conservation translocation The progress of the reintroduction will be success across major taxa. documented in technical and peer-reviewed publications allowing it to be considered in meta- analyses. • Publication in peer-reviewed media confers an The project outcomes and any incidental assurance of quality, and permanent, formal information will be reported in peer-reviewed citation; this allows publications to be sourced publications. and become a resource for any subsequent evidence-based, systematic reviews. 4. Information should be disseminated in Information will be disseminated in English in a languages and formats best suited to serve variety of formats as appropriate to interested essential and interested parties and parties and organisations (section 11 of this organisations. plan).

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Appendix 3: Captive loan agreement

This text provides suggested wording, to be assessed and agreed with Natural England.

The Northern Pool Frog Captive Loan Programme will be managed by The Amphibian and Reptile Conservation Trust (hereafter, the “programme managers”). Terms of agreement concerning the loan of northern pool frogs are as follows:

1. Animals will be held as educational exhibits and not to provide reintroduction stock.

2. Animals will be displayed with interpretative material, the content of which will be agreed with the programme managers who will provide relevant information.

3. Animals will be suitably accommodated and cared for. The stock will be appropriately managed to guard against substantial increases in captive population size, unless agreed with the programme managers.

4. Neither the original stock nor the progeny will be transferred to another party other than with agreement of the programme managers.

5. Neither the original stock nor the progeny will be released into the wild.

6. No other water frogs (genus Pelophylax) will be maintained by holding organisations so that there is no risk to genetic integrity.

7. The programme managers will have the right to inspect both the animals and their accommodation at any reasonable time, upon giving satisfactory notice to the holding organisation.

8. In the event of death of an animal, where practicable, it will made available for post-mortem examination.

9. Both original stock and their progeny will remain the property of Natural England.

On behalf of the holding organisation:

Name ......

Position: ......

Signed ......

Dated ......

On behalf of Amphibian and Reptile Conservation:

Name ......

Position: ......

Signed ......

Dated ......

[ENDS.]

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